diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/00-INDEX | 2 | ||||
| -rw-r--r-- | Documentation/CodingStyle | 42 | ||||
| -rw-r--r-- | Documentation/DocBook/procfs-guide.tmpl | 4 | ||||
| -rw-r--r-- | Documentation/accounting/delay-accounting.txt | 11 | ||||
| -rw-r--r-- | Documentation/accounting/getdelays.c | 8 | ||||
| -rw-r--r-- | Documentation/accounting/taskstats-struct.txt | 7 | ||||
| -rw-r--r-- | Documentation/bt8xxgpio.txt | 67 | ||||
| -rw-r--r-- | Documentation/controllers/memory.txt | 3 | ||||
| -rw-r--r-- | Documentation/edac.txt | 151 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 18 | ||||
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 8 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 135 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 7 | ||||
| -rw-r--r-- | Documentation/moxa-smartio | 392 | ||||
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 57 | ||||
| -rw-r--r-- | Documentation/unaligned-memory-access.txt | 32 |
16 files changed, 661 insertions, 283 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index 1977fab38656..6de71308a906 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -361,8 +361,6 @@ telephony/ - directory with info on telephony (e.g. voice over IP) support. time_interpolators.txt - info on time interpolators. -tipar.txt - - information about Parallel link cable for Texas Instruments handhelds. tty.txt - guide to the locking policies of the tty layer. uml/ diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle index 6caa14615578..1875e502f872 100644 --- a/Documentation/CodingStyle +++ b/Documentation/CodingStyle @@ -474,25 +474,29 @@ make a good program). So, you can either get rid of GNU emacs, or change it to use saner values. To do the latter, you can stick the following in your .emacs file: -(defun linux-c-mode () - "C mode with adjusted defaults for use with the Linux kernel." - (interactive) - (c-mode) - (c-set-style "K&R") - (setq tab-width 8) - (setq indent-tabs-mode t) - (setq c-basic-offset 8)) - -This will define the M-x linux-c-mode command. When hacking on a -module, if you put the string -*- linux-c -*- somewhere on the first -two lines, this mode will be automatically invoked. Also, you may want -to add - -(setq auto-mode-alist (cons '("/usr/src/linux.*/.*\\.[ch]$" . linux-c-mode) - auto-mode-alist)) - -to your .emacs file if you want to have linux-c-mode switched on -automagically when you edit source files under /usr/src/linux. +(defun c-lineup-arglist-tabs-only (ignored) + "Line up argument lists by tabs, not spaces" + (let* ((anchor (c-langelem-pos c-syntactic-element)) + (column (c-langelem-2nd-pos c-syntactic-element)) + (offset (- (1+ column) anchor)) + (steps (floor offset c-basic-offset))) + (* (max steps 1) + c-basic-offset))) + +(add-hook 'c-mode-hook + (lambda () + (let ((filename (buffer-file-name))) + ;; Enable kernel mode for the appropriate files + (when (and filename + (string-match "~/src/linux-trees" filename)) + (setq indent-tabs-mode t) + (c-set-style "linux") + (c-set-offset 'arglist-cont-nonempty + '(c-lineup-gcc-asm-reg + c-lineup-arglist-tabs-only)))))) + +This will make emacs go better with the kernel coding style for C +files below ~/src/linux-trees. But even if you fail in getting emacs to do sane formatting, not everything is lost: use "indent". diff --git a/Documentation/DocBook/procfs-guide.tmpl b/Documentation/DocBook/procfs-guide.tmpl index 1fd6a1ec7591..8a5dc6e021ff 100644 --- a/Documentation/DocBook/procfs-guide.tmpl +++ b/Documentation/DocBook/procfs-guide.tmpl @@ -29,12 +29,12 @@ <revhistory> <revision> - <revnumber>1.0 </revnumber> + <revnumber>1.0</revnumber> <date>May 30, 2001</date> <revremark>Initial revision posted to linux-kernel</revremark> </revision> <revision> - <revnumber>1.1 </revnumber> + <revnumber>1.1</revnumber> <date>June 3, 2001</date> <revremark>Revised after comments from linux-kernel</revremark> </revision> diff --git a/Documentation/accounting/delay-accounting.txt b/Documentation/accounting/delay-accounting.txt index 1443cd71d263..8a12f0730c94 100644 --- a/Documentation/accounting/delay-accounting.txt +++ b/Documentation/accounting/delay-accounting.txt @@ -11,6 +11,7 @@ the delays experienced by a task while a) waiting for a CPU (while being runnable) b) completion of synchronous block I/O initiated by the task c) swapping in pages +d) memory reclaim and makes these statistics available to userspace through the taskstats interface. @@ -41,7 +42,7 @@ this structure. See include/linux/taskstats.h for a description of the fields pertaining to delay accounting. It will generally be in the form of counters returning the cumulative -delay seen for cpu, sync block I/O, swapin etc. +delay seen for cpu, sync block I/O, swapin, memory reclaim etc. Taking the difference of two successive readings of a given counter (say cpu_delay_total) for a task will give the delay @@ -94,7 +95,9 @@ CPU count real total virtual total delay total 7876 92005750 100000000 24001500 IO count delay total 0 0 -MEM count delay total +SWAP count delay total + 0 0 +RECLAIM count delay total 0 0 Get delays seen in executing a given simple command @@ -108,5 +111,7 @@ CPU count real total virtual total delay total 6 4000250 4000000 0 IO count delay total 0 0 -MEM count delay total +SWAP count delay total + 0 0 +RECLAIM count delay total 0 0 diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c index 40121b5cca14..3f7755f3963f 100644 --- a/Documentation/accounting/getdelays.c +++ b/Documentation/accounting/getdelays.c @@ -196,14 +196,18 @@ void print_delayacct(struct taskstats *t) " %15llu%15llu%15llu%15llu\n" "IO %15s%15s\n" " %15llu%15llu\n" - "MEM %15s%15s\n" + "SWAP %15s%15s\n" + " %15llu%15llu\n" + "RECLAIM %12s%15s\n" " %15llu%15llu\n", "count", "real total", "virtual total", "delay total", t->cpu_count, t->cpu_run_real_total, t->cpu_run_virtual_total, t->cpu_delay_total, "count", "delay total", t->blkio_count, t->blkio_delay_total, - "count", "delay total", t->swapin_count, t->swapin_delay_total); + "count", "delay total", t->swapin_count, t->swapin_delay_total, + "count", "delay total", + t->freepages_count, t->freepages_delay_total); } void task_context_switch_counts(struct taskstats *t) diff --git a/Documentation/accounting/taskstats-struct.txt b/Documentation/accounting/taskstats-struct.txt index cd784f46bf8a..b988d110db59 100644 --- a/Documentation/accounting/taskstats-struct.txt +++ b/Documentation/accounting/taskstats-struct.txt @@ -26,6 +26,8 @@ There are three different groups of fields in the struct taskstats: 5) Time accounting for SMT machines +6) Extended delay accounting fields for memory reclaim + Future extension should add fields to the end of the taskstats struct, and should not change the relative position of each field within the struct. @@ -170,4 +172,9 @@ struct taskstats { __u64 ac_utimescaled; /* utime scaled on frequency etc */ __u64 ac_stimescaled; /* stime scaled on frequency etc */ __u64 cpu_scaled_run_real_total; /* scaled cpu_run_real_total */ + +6) Extended delay accounting fields for memory reclaim + /* Delay waiting for memory reclaim */ + __u64 freepages_count; + __u64 freepages_delay_total; } diff --git a/Documentation/bt8xxgpio.txt b/Documentation/bt8xxgpio.txt new file mode 100644 index 000000000000..d8297e4ebd26 --- /dev/null +++ b/Documentation/bt8xxgpio.txt @@ -0,0 +1,67 @@ +=============================================================== +== BT8XXGPIO driver == +== == +== A driver for a selfmade cheap BT8xx based PCI GPIO-card == +== == +== For advanced documentation, see == +== http://www.bu3sch.de/btgpio.php == +=============================================================== + + +A generic digital 24-port PCI GPIO card can be built out of an ordinary +Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The +Brooktree chip is used in old analog Hauppauge WinTV PCI cards. You can easily +find them used for low prices on the net. + +The bt8xx chip does have 24 digital GPIO ports. +These ports are accessible via 24 pins on the SMD chip package. + + +============================================== +== How to physically access the GPIO pins == +============================================== + +The are several ways to access these pins. One might unsolder the whole chip +and put it on a custom PCI board, or one might only unsolder each individual +GPIO pin and solder that to some tiny wire. As the chip package really is tiny +there are some advanced soldering skills needed in any case. + +The physical pinouts are drawn in the following ASCII art. +The GPIO pins are marked with G00-G23 + + G G G G G G G G G G G G G G G G G G + 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 + | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + --------------------------------------------------------------------------- + --| ^ ^ |-- + --| pin 86 pin 67 |-- + --| |-- + --| pin 61 > |-- G18 + --| |-- G19 + --| |-- G20 + --| |-- G21 + --| |-- G22 + --| pin 56 > |-- G23 + --| |-- + --| Brooktree 878/879 |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| |-- + --| O |-- + --| |-- + --------------------------------------------------------------------------- + | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + ^ + This is pin 1 + diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt index 866b9cd9a959..9b53d5827361 100644 --- a/Documentation/controllers/memory.txt +++ b/Documentation/controllers/memory.txt @@ -242,8 +242,7 @@ rmdir() if there are no tasks. 1. Add support for accounting huge pages (as a separate controller) 2. Make per-cgroup scanner reclaim not-shared pages first 3. Teach controller to account for shared-pages -4. Start reclamation when the limit is lowered -5. Start reclamation in the background when the limit is +4. Start reclamation in the background when the limit is not yet hit but the usage is getting closer Summary diff --git a/Documentation/edac.txt b/Documentation/edac.txt index a5c36842ecef..ced527388001 100644 --- a/Documentation/edac.txt +++ b/Documentation/edac.txt @@ -222,74 +222,9 @@ both csrow2 and csrow3 are populated, this indicates a dual ranked set of DIMMs for channels 0 and 1. -Within each of the 'mc','mcX' and 'csrowX' directories are several +Within each of the 'mcX' and 'csrowX' directories are several EDAC control and attribute files. - -============================================================================ -DIRECTORY 'mc' - -In directory 'mc' are EDAC system overall control and attribute files: - - -Panic on UE control file: - - 'edac_mc_panic_on_ue' - - An uncorrectable error will cause a machine panic. This is usually - desirable. It is a bad idea to continue when an uncorrectable error - occurs - it is indeterminate what was uncorrected and the operating - system context might be so mangled that continuing will lead to further - corruption. If the kernel has MCE configured, then EDAC will never - notice the UE. - - LOAD TIME: module/kernel parameter: panic_on_ue=[0|1] - - RUN TIME: echo "1" >/sys/devices/system/edac/mc/edac_mc_panic_on_ue - - -Log UE control file: - - 'edac_mc_log_ue' - - Generate kernel messages describing uncorrectable errors. These errors - are reported through the system message log system. UE statistics - will be accumulated even when UE logging is disabled. - - LOAD TIME: module/kernel parameter: log_ue=[0|1] - - RUN TIME: echo "1" >/sys/devices/system/edac/mc/edac_mc_log_ue - - -Log CE control file: - - 'edac_mc_log_ce' - - Generate kernel messages describing correctable errors. These - errors are reported through the system message log system. - CE statistics will be accumulated even when CE logging is disabled. - - LOAD TIME: module/kernel parameter: log_ce=[0|1] - - RUN TIME: echo "1" >/sys/devices/system/edac/mc/edac_mc_log_ce - - -Polling period control file: - - 'edac_mc_poll_msec' - - The time period, in milliseconds, for polling for error information. - Too small a value wastes resources. Too large a value might delay - necessary handling of errors and might loose valuable information for - locating the error. 1000 milliseconds (once each second) is the current - default. Systems which require all the bandwidth they can get, may - increase this. - - LOAD TIME: module/kernel parameter: poll_msec=[0|1] - - RUN TIME: echo "1000" >/sys/devices/system/edac/mc/edac_mc_poll_msec - - ============================================================================ 'mcX' DIRECTORIES @@ -537,7 +472,6 @@ Channel 1 DIMM Label control file: motherboard specific and determination of this information must occur in userland at this time. - ============================================================================ SYSTEM LOGGING @@ -570,7 +504,6 @@ error type, a notice of "no info" and then an optional, driver-specific error message. - ============================================================================ PCI Bus Parity Detection @@ -604,6 +537,74 @@ Enable/Disable PCI Parity checking control file: echo "0" >/sys/devices/system/edac/pci/check_pci_parity +Parity Count: + + 'pci_parity_count' + + This attribute file will display the number of parity errors that + have been detected. + + +============================================================================ +MODULE PARAMETERS + +Panic on UE control file: + + 'edac_mc_panic_on_ue' + + An uncorrectable error will cause a machine panic. This is usually + desirable. It is a bad idea to continue when an uncorrectable error + occurs - it is indeterminate what was uncorrected and the operating + system context might be so mangled that continuing will lead to further + corruption. If the kernel has MCE configured, then EDAC will never + notice the UE. + + LOAD TIME: module/kernel parameter: edac_mc_panic_on_ue=[0|1] + + RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_panic_on_ue + + +Log UE control file: + + 'edac_mc_log_ue' + + Generate kernel messages describing uncorrectable errors. These errors + are reported through the system message log system. UE statistics + will be accumulated even when UE logging is disabled. + + LOAD TIME: module/kernel parameter: edac_mc_log_ue=[0|1] + + RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ue + + +Log CE control file: + + 'edac_mc_log_ce' + + Generate kernel messages describing correctable errors. These + errors are reported through the system message log system. + CE statistics will be accumulated even when CE logging is disabled. + + LOAD TIME: module/kernel parameter: edac_mc_log_ce=[0|1] + + RUN TIME: echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ce + + +Polling period control file: + + 'edac_mc_poll_msec' + + The time period, in milliseconds, for polling for error information. + Too small a value wastes resources. Too large a value might delay + necessary handling of errors and might loose valuable information for + locating the error. 1000 milliseconds (once each second) is the current + default. Systems which require all the bandwidth they can get, may + increase this. + + LOAD TIME: module/kernel parameter: edac_mc_poll_msec=[0|1] + + RUN TIME: echo "1000" > /sys/module/edac_core/parameters/edac_mc_poll_msec + Panic on PCI PARITY Error: @@ -614,21 +615,13 @@ Panic on PCI PARITY Error: error has been detected. - module/kernel parameter: panic_on_pci_parity=[0|1] + module/kernel parameter: edac_panic_on_pci_pe=[0|1] Enable: - echo "1" >/sys/devices/system/edac/pci/panic_on_pci_parity + echo "1" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe Disable: - echo "0" >/sys/devices/system/edac/pci/panic_on_pci_parity - - -Parity Count: - - 'pci_parity_count' - - This attribute file will display the number of parity errors that - have been detected. + echo "0" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 09c4a1efb8e3..721c71b86e06 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -138,24 +138,6 @@ Who: Kay Sievers <kay.sievers@suse.de> --------------------------- -What: find_task_by_pid -When: 2.6.26 -Why: With pid namespaces, calling this funciton will return the - wrong task when called from inside a namespace. - - The best way to save a task pid and find a task by this - pid later, is to find this task's struct pid pointer (or get - it directly from the task) and call pid_task() later. - - If someone really needs to get a task by its pid_t, then - he most likely needs the find_task_by_vpid() to get the - task from the same namespace as the current task is in, but - this may be not so in general. - -Who: Pavel Emelyanov <xemul@openvz.org> - ---------------------------- - What: ACPI procfs interface When: July 2008 Why: ACPI sysfs conversion should be finished by January 2008. diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index 2d5e1e582e13..bbac4f1d9056 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -96,6 +96,14 @@ shortname=lower|win95|winnt|mixed emulate the Windows 95 rule for create. Default setting is `lower'. +tz=UTC -- Interpret timestamps as UTC rather than local time. + This option disables the conversion of timestamps + between local time (as used by Windows on FAT) and UTC + (which Linux uses internally). This is particuluarly + useful when mounting devices (like digital cameras) + that are set to UTC in order to avoid the pitfalls of + local time. + <bool>: 0,1,yes,no,true,false TODO diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index c35ca9e40d4c..18022e249c53 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -347,15 +347,12 @@ necessarily be nonportable. Dynamic definition of GPIOs is not currently standard; for example, as a side effect of configuring an add-on board with some GPIO expanders. -These calls are purely for kernel space, but a userspace API could be built -on top of them. - GPIO implementor's framework (OPTIONAL) ======================================= As noted earlier, there is an optional implementation framework making it easier for platforms to support different kinds of GPIO controller using -the same programming interface. +the same programming interface. This framework is called "gpiolib". As a debugging aid, if debugfs is available a /sys/kernel/debug/gpio file will be found there. That will list all the controllers registered through @@ -392,11 +389,21 @@ either NULL or the label associated with that GPIO when it was requested. Platform Support ---------------- -To support this framework, a platform's Kconfig will "select HAVE_GPIO_LIB" +To support this framework, a platform's Kconfig will "select" either +ARCH_REQUIRE_GPIOLIB or ARCH_WANT_OPTIONAL_GPIOLIB and arrange that its <asm/gpio.h> includes <asm-generic/gpio.h> and defines three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep(). They may also want to provide a custom value for ARCH_NR_GPIOS. +ARCH_REQUIRE_GPIOLIB means that the gpio-lib code will always get compiled +into the kernel on that architecture. + +ARCH_WANT_OPTIONAL_GPIOLIB means the gpio-lib code defaults to off and the user +can enable it and build it into the kernel optionally. + +If neither of these options are selected, the platform does not support +GPIOs through GPIO-lib and the code cannot be enabled by the user. + Trivial implementations of those functions can directly use framework code, which always dispatches through the gpio_chip: @@ -439,4 +446,120 @@ becomes available. That may mean the device should not be registered until calls for that GPIO can work. One way to address such dependencies is for such gpio_chip controllers to provide setup() and teardown() callbacks to board specific code; those board specific callbacks would register devices -once all the necessary resources are available. +once all the necessary resources are available, and remove them later when +the GPIO controller device becomes unavailable. + + +Sysfs Interface for Userspace (OPTIONAL) +======================================== +Platforms which use the "gpiolib" implementors framework may choose to +configure a sysfs user interface to GPIOs. This is different from the +debugfs interface, since it provides control over GPIO direction and +value instead of just showing a gpio state summary. Plus, it could be +present on production systems without debugging support. + +Given approprate hardware documentation for the system, userspace could +know for example that GPIO #23 controls the write protect line used to +protect boot loader segments in flash memory. System upgrade procedures +may need to temporarily remove that protection, first importing a GPIO, +then changing its output state, then updating the code before re-enabling +the write protection. In normal use, GPIO #23 would never be touched, +and the kernel would have no need to know about it. + +Again depending on appropriate hardware documentation, on some systems +userspace GPIO can be used to determine system configuration data that +standard kernels won't know about. And for some tasks, simple userspace +GPIO drivers could be all that the system really needs. + +Note that standard kernel drivers exist for common "LEDs and Buttons" +GPIO tasks: "leds-gpio" and "gpio_keys", respectively. Use those +instead of talking directly to the GPIOs; they integrate with kernel +frameworks better than your userspace code could. + + +Paths in Sysfs +-------------- +There are three kinds of entry in /sys/class/gpio: + + - Control interfaces used to get userspace control over GPIOs; + + - GPIOs themselves; and + + - GPIO controllers ("gpio_chip" instances). + +That's in addition to standard files including the "device" symlink. + +The control interfaces are write-only: + + /sys/class/gpio/ + + "export" ... Userspace may ask the kernel to export control of + a GPIO to userspace by writing its number to this file. + + Example: "echo 19 > export" will create a "gpio19" node + for GPIO #19, if that's not requested by kernel code. + + "unexport" ... Reverses the effect of exporting to userspace. + + Example: "echo 19 > unexport" will remove a "gpio19" + node exported using the "export" file. + +GPIO signals have paths like /sys/class/gpio/gpio42/ (for GPIO #42) +and have the following read/write attributes: + + /sys/class/gpio/gpioN/ + + "direction" ... reads as either "in" or "out". This value may + normally be written. Writing as "out" defaults to + initializing the value as low. To ensure glitch free + operation, values "low" and "high" may be written to + configure the GPIO as an output with that initial value. + + Note that this attribute *will not exist* if the kernel + doesn't support changing the direction of a GPIO, or + it was exported by kernel code that didn't explicitly + allow userspace to reconfigure this GPIO's direction. + + "value" ... reads as either 0 (low) or 1 (high). If the GPIO + is configured as an output, this value may be written; + any nonzero value is treated as high. + +GPIO controllers have paths like /sys/class/gpio/chipchip42/ (for the +controller implementing GPIOs starting at #42) and have the following +read-only attributes: + + /sys/class/gpio/gpiochipN/ + + "base" ... same as N, the first GPIO managed by this chip + + "label" ... provided for diagnostics (not always unique) + + "ngpio" ... how many GPIOs this manges (N to N + ngpio - 1) + +Board documentation should in most cases cover what GPIOs are used for +what purposes. However, those numbers are not always stable; GPIOs on +a daughtercard might be different depending on the base board being used, +or other cards in the stack. In such cases, you may need to use the +gpiochip nodes (possibly in conjunction with schematics) to determine +the correct GPIO number to use for a given signal. + + +Exporting from Kernel code +-------------------------- +Kernel code can explicitly manage exports of GPIOs which have already been +requested using gpio_request(): + + /* export the GPIO to userspace */ + int gpio_export(unsigned gpio, bool direction_may_change); + + /* reverse gpio_export() */ + void gpio_unexport(); + +After a kernel driver requests a GPIO, it may only be made available in +the sysfs interface by gpio_export(). The driver can control whether the +signal direction may change. This helps drivers prevent userspace code +from accidentally clobbering important system state. + +This explicit exporting can help with debugging (by making some kinds +of experiments easier), or can provide an always-there interface that's +suitable for documenting as part of a board support package. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4328307a875c..0f130a4f9ba3 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2165,13 +2165,6 @@ and is between 256 and 4096 characters. It is defined in the file <deci-seconds>: poll all this frequency 0: no polling (default) - tipar.timeout= [HW,PPT] - Set communications timeout in tenths of a second - (default 15). - - tipar.delay= [HW,PPT] - Set inter-bit delay in microseconds (default 10). - tmscsim= [HW,SCSI] See comment before function dc390_setup() in drivers/scsi/tmscsim.c. diff --git a/Documentation/moxa-smartio b/Documentation/moxa-smartio index fe24ecc6372e..5337e80a5b96 100644 --- a/Documentation/moxa-smartio +++ b/Documentation/moxa-smartio @@ -1,14 +1,22 @@ ============================================================================= - - MOXA Smartio Family Device Driver Ver 1.1 Installation Guide - for Linux Kernel 2.2.x and 2.0.3x - Copyright (C) 1999, Moxa Technologies Co, Ltd. + MOXA Smartio/Industio Family Device Driver Installation Guide + for Linux Kernel 2.4.x, 2.6.x + Copyright (C) 2008, Moxa Inc. ============================================================================= +Date: 01/21/2008 + Content 1. Introduction 2. System Requirement 3. Installation + 3.1 Hardware installation + 3.2 Driver files + 3.3 Device naming convention + 3.4 Module driver configuration + 3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x. + 3.6 Custom configuration + 3.7 Verify driver installation 4. Utilities 5. Setserial 6. Troubleshooting @@ -16,27 +24,48 @@ Content ----------------------------------------------------------------------------- 1. Introduction - The Smartio family Linux driver, Ver. 1.1, supports following multiport + The Smartio/Industio/UPCI family Linux driver supports following multiport boards. - -C104P/H/HS, C104H/PCI, C104HS/PCI, CI-104J 4 port multiport board. - -C168P/H/HS, C168H/PCI 8 port multiport board. - - This driver has been modified a little and cleaned up from the Moxa - contributed driver code and merged into Linux 2.2.14pre. In particular - official major/minor numbers have been assigned which are different to - those the original Moxa supplied driver used. + - 2 ports multiport board + CP-102U, CP-102UL, CP-102UF + CP-132U-I, CP-132UL, + CP-132, CP-132I, CP132S, CP-132IS, + CI-132, CI-132I, CI-132IS, + (C102H, C102HI, C102HIS, C102P, CP-102, CP-102S) + + - 4 ports multiport board + CP-104EL, + CP-104UL, CP-104JU, + CP-134U, CP-134U-I, + C104H/PCI, C104HS/PCI, + CP-114, CP-114I, CP-114S, CP-114IS, CP-114UL, + C104H, C104HS, + CI-104J, CI-104JS, + CI-134, CI-134I, CI-134IS, + (C114HI, CT-114I, C104P) + POS-104UL, + CB-114, + CB-134I + + - 8 ports multiport board + CP-118EL, CP-168EL, + CP-118U, CP-168U, + C168H/PCI, + C168H, C168HS, + (C168P), + CB-108 This driver and installation procedure have been developed upon Linux Kernel - 2.2.5 and backward compatible to 2.0.3x. This driver supports Intel x86 and - Alpha hardware platform. In order to maintain compatibility, this version - has also been properly tested with RedHat, OpenLinux, TurboLinux and - S.u.S.E Linux. However, if compatibility problem occurs, please contact - Moxa at support@moxa.com.tw. + 2.4.x and 2.6.x. This driver supports Intel x86 hardware platform. In order + to maintain compatibility, this version has also been properly tested with + RedHat, Mandrake, Fedora and S.u.S.E Linux. However, if compatibility problem + occurs, please contact Moxa at support@moxa.com.tw. In addition to device driver, useful utilities are also provided in this version. They are - - msdiag Diagnostic program for detecting installed Moxa Smartio boards. + - msdiag Diagnostic program for displaying installed Moxa + Smartio/Industio boards. - msmon Monitor program to observe data count and line status signals. - msterm A simple terminal program which is useful in testing serial ports. @@ -47,8 +76,7 @@ Content GNU General Public License in this version. Please refer to GNU General Public License announcement in each source code file for more detail. - In Moxa's ftp sites, you may always find latest driver at - ftp://ftp.moxa.com or ftp://ftp.moxa.com.tw. + In Moxa's Web sites, you may always find latest driver at http://web.moxa.com. This version of driver can be installed as Loadable Module (Module driver) or built-in into kernel (Static driver). You may refer to following @@ -61,8 +89,8 @@ Content ----------------------------------------------------------------------------- 2. System Requirement - - Hardware platform: Intel x86 or Alpha machine - - Kernel version: 2.0.3x or 2.2.x + - Hardware platform: Intel x86 machine + - Kernel version: 2.4.x or 2.6.x - gcc version 2.72 or later - Maximum 4 boards can be installed in combination @@ -70,9 +98,18 @@ Content 3. Installation 3.1 Hardware installation + 3.2 Driver files + 3.3 Device naming convention + 3.4 Module driver configuration + 3.5 Static driver configuration for Linux kernel 2.4.x, 2.6.x. + 3.6 Custom configuration + 3.7 Verify driver installation + + + 3.1 Hardware installation - There are two types of buses, ISA and PCI, for Smartio family multiport - board. + There are two types of buses, ISA and PCI, for Smartio/Industio + family multiport board. ISA board --------- @@ -81,47 +118,57 @@ Content installation procedure in User's Manual before proceed any further. Please make sure the JP1 is open after the ISA board is set properly. - PCI board - --------- + PCI/UPCI board + -------------- You may need to adjust IRQ usage in BIOS to avoid from IRQ conflict with other ISA devices. Please refer to hardware installation procedure in User's Manual in advance. - IRQ Sharing + PCI IRQ Sharing ----------- Each port within the same multiport board shares the same IRQ. Up to - 4 Moxa Smartio Family multiport boards can be installed together on - one system and they can share the same IRQ. + 4 Moxa Smartio/Industio PCI Family multiport boards can be installed + together on one system and they can share the same IRQ. + - 3.2 Driver files and device naming convention + 3.2 Driver files The driver file may be obtained from ftp, CD-ROM or floppy disk. The first step, anyway, is to copy driver file "mxser.tgz" into specified directory. e.g. /moxa. The execute commands as below. + # cd / + # mkdir moxa # cd /moxa - # tar xvf /dev/fd0 + # tar xvf /dev/fd0 + or + + # cd / + # mkdir moxa # cd /moxa # cp /mnt/cdrom/<driver directory>/mxser.tgz . # tar xvfz mxser.tgz + + 3.3 Device naming convention + You may find all the driver and utilities files in /moxa/mxser. Following installation procedure depends on the model you'd like to - run the driver. If you prefer module driver, please refer to 3.3. - If static driver is required, please refer to 3.4. + run the driver. If you prefer module driver, please refer to 3.4. + If static driver is required, please refer to 3.5. Dialin and callout port ----------------------- - This driver remains traditional serial device properties. There're + This driver remains traditional serial device properties. There are two special file name for each serial port. One is dial-in port which is named "ttyMxx". For callout port, the naming convention is "cumxx". Device naming when more than 2 boards installed ----------------------------------------------- - Naming convention for each Smartio multiport board is pre-defined - as below. + Naming convention for each Smartio/Industio multiport board is + pre-defined as below. Board Num. Dial-in Port Callout port 1st board ttyM0 - ttyM7 cum0 - cum7 @@ -129,6 +176,12 @@ Content 3rd board ttyM16 - ttyM23 cum16 - cum23 4th board ttyM24 - ttym31 cum24 - cum31 + + !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + Under Kernel 2.6 the cum Device is Obsolete. So use ttyM* + device instead. + !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + Board sequence -------------- This driver will activate ISA boards according to the parameter set @@ -138,69 +191,131 @@ Content For PCI boards, their sequence will be after ISA boards and C168H/PCI has higher priority than C104H/PCI boards. - 3.3 Module driver configuration + 3.4 Module driver configuration Module driver is easiest way to install. If you prefer static driver installation, please skip this paragraph. - 1. Find "Makefile" in /moxa/mxser, then run - # make install + + ------------- Prepare to use the MOXA driver-------------------- + 3.4.1 Create tty device with correct major number + Before using MOXA driver, your system must have the tty devices + which are created with driver's major number. We offer one shell + script "msmknod" to simplify the procedure. + This step is only needed to be executed once. But you still + need to do this procedure when: + a. You change the driver's major number. Please refer the "3.7" + section. + b. Your total installed MOXA boards number is changed. Maybe you + add/delete one MOXA board. + c. You want to change the tty name. This needs to modify the + shell script "msmknod" + + The procedure is: + # cd /moxa/mxser/driver + # ./msmknod + + This shell script will require the major number for dial-in + device and callout device to create tty device. You also need + to specify the total installed MOXA board number. Default major + numbers for dial-in device and callout device are 30, 35. If + you need to change to other number, please refer section "3.7" + for more detailed procedure. + Msmknod will delete any special files occupying the same device + naming. + + 3.4.2 Build the MOXA driver and utilities + Before using the MOXA driver and utilities, you need compile the + all the source code. This step is only need to be executed once. + But you still re-compile the source code if you modify the source + code. For example, if you change the driver's major number (see + "3.7" section), then you need to do this step again. + + Find "Makefile" in /moxa/mxser, then run + + # make clean; make install + + !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!! + For Red Hat 9, Red Hat Enterprise Linux AS3/ES3/WS3 & Fedora Core1: + # make clean; make installsp1 + + For Red Hat Enterprise Linux AS4/ES4/WS4: + # make clean; make installsp2 + !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!! The driver files "mxser.o" and utilities will be properly compiled - and copied to system directories respectively.Then run + and copied to system directories respectively. - # insmod mxser + ------------- Load MOXA driver-------------------- + 3.4.3 Load the MOXA driver - to activate the modular driver. You may run "lsmod" to check - if "mxser.o" is activated. + # modprobe mxser <argument> - 2. Create special files by executing "msmknod". - # cd /moxa/mxser/driver - # ./msmknod + will activate the module driver. You may run "lsmod" to check + if "mxser" is activated. If the MOXA board is ISA board, the + <argument> is needed. Please refer to section "3.4.5" for more + information. + + + ------------- Load MOXA driver on boot -------------------- + 3.4.4 For the above description, you may manually execute + "modprobe mxser" to activate this driver and run + "rmmod mxser" to remove it. + However, it's better to have a boot time configuration to + eliminate manual operation. Boot time configuration can be + achieved by rc file. We offer one "rc.mxser" file to simplify + the procedure under "moxa/mxser/driver". - Default major numbers for dial-in device and callout device are - 174, 175. Msmknod will delete any special files occupying the same - device naming. + But if you use ISA board, please modify the "modprobe ..." command + to add the argument (see "3.4.5" section). After modifying the + rc.mxser, please try to execute "/moxa/mxser/driver/rc.mxser" + manually to make sure the modification is ok. If any error + encountered, please try to modify again. If the modification is + completed, follow the below step. - 3. Up to now, you may manually execute "insmod mxser" to activate - this driver and run "rmmod mxser" to remove it. However, it's - better to have a boot time configuration to eliminate manual - operation. - Boot time configuration can be achieved by rc file. Run following - command for setting rc files. + Run following command for setting rc files. # cd /moxa/mxser/driver # cp ./rc.mxser /etc/rc.d # cd /etc/rc.d - You may have to modify part of the content in rc.mxser to specify - parameters for ISA board. Please refer to rc.mxser for more detail. - Find "rc.serial". If "rc.serial" doesn't exist, create it by vi. - Add "rc.mxser" in last line. Next, open rc.local by vi - and append following content. + Check "rc.serial" is existed or not. If "rc.serial" doesn't exist, + create it by vi, run "chmod 755 rc.serial" to change the permission. + Add "/etc/rc.d/rc.mxser" in last line, - if [ -f /etc/rc.d/rc.serial ]; then - sh /etc/rc.d/rc.serial - fi + Reboot and check if moxa.o activated by "lsmod" command. - 4. Reboot and check if mxser.o activated by "lsmod" command. - 5. If you'd like to drive Smartio ISA boards in the system, you'll - have to add parameter to specify CAP address of given board while - activating "mxser.o". The format for parameters are as follows. + 3.4.5. If you'd like to drive Smartio/Industio ISA boards in the system, + you'll have to add parameter to specify CAP address of given + board while activating "mxser.o". The format for parameters are + as follows. - insmod mxser ioaddr=0x???,0x???,0x???,0x??? + modprobe mxser ioaddr=0x???,0x???,0x???,0x??? | | | | | | | +- 4th ISA board | | +------ 3rd ISA board | +------------ 2nd ISA board +------------------- 1st ISA board - 3.4 Static driver configuration + 3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x + + Note: To use static driver, you must install the linux kernel + source package. + + 3.5.1 Backup the built-in driver in the kernel. + # cd /usr/src/linux/drivers/char + # mv mxser.c mxser.c.old + + For Red Hat 7.x user, you need to create link: + # cd /usr/src + # ln -s linux-2.4 linux - 1. Create link + 3.5.2 Create link # cd /usr/src/linux/drivers/char # ln -s /moxa/mxser/driver/mxser.c mxser.c - 2. Add CAP address list for ISA boards + 3.5.3 Add CAP address list for ISA boards. For PCI boards user, + please skip this step. + In module mode, the CAP address for ISA board is given by parameter. In static driver configuration, you'll have to assign it within driver's source code. If you will not @@ -222,73 +337,55 @@ Content static int mxserBoardCAP[] = {0x280, 0x180, 0x00, 0x00}; - 3. Modify tty_io.c - # cd /usr/src/linux/drivers/char/ - # vi tty_io.c - Find pty_init(), insert "mxser_init()" as + 3.5.4 Setup kernel configuration - pty_init(); - mxser_init(); + Configure the kernel: - 4. Modify tty.h - # cd /usr/src/linux/include/linux - # vi tty.h - Find extern int tty_init(void), insert "mxser_init()" as + # cd /usr/src/linux + # make menuconfig - extern int tty_init(void); - extern int mxser_init(void); - - 5. Modify Makefile - # cd /usr/src/linux/drivers/char - # vi Makefile - Find L_OBJS := tty_io.o ...... random.o, add - "mxser.o" at last of this line as - L_OBJS := tty_io.o ....... mxser.o + You will go into a menu-driven system. Please select [Character + devices][Non-standard serial port support], enable the [Moxa + SmartIO support] driver with "[*]" for built-in (not "[M]"), then + select [Exit] to exit this program. - 6. Rebuild kernel - The following are for Linux kernel rebuilding,for your reference only. + 3.5.5 Rebuild kernel + The following are for Linux kernel rebuilding, for your + reference only. For appropriate details, please refer to the Linux document. - If 'lilo' utility is installed, please use 'make zlilo' to rebuild - kernel. If 'lilo' is not installed, please follow the following steps. - a. cd /usr/src/linux - b. make clean /* take a few minutes */ - c. make bzImage /* take probably 10-20 minutes */ - d. Backup original boot kernel. /* optional step */ - e. cp /usr/src/linux/arch/i386/boot/bzImage /boot/vmlinuz + b. make clean /* take a few minutes */ + c. make dep /* take a few minutes */ + d. make bzImage /* take probably 10-20 minutes */ + e. make install /* copy boot image to correct position */ f. Please make sure the boot kernel (vmlinuz) is in the - correct position. If you use 'lilo' utility, you should - check /etc/lilo.conf 'image' item specified the path - which is the 'vmlinuz' path, or you will load wrong - (or old) boot kernel image (vmlinuz). - g. chmod 400 /vmlinuz - h. lilo - i. rdev -R /vmlinuz 1 - j. sync - - Note that if the result of "make zImage" is ERROR, then you have to - go back to Linux configuration Setup. Type "make config" in directory - /usr/src/linux or "setup". - - Since system include file, /usr/src/linux/include/linux/interrupt.h, - is modified each time the MOXA driver is installed, kernel rebuilding - is inevitable. And it takes about 10 to 20 minutes depends on the - machine. - - 7. Make utility - # cd /moxa/mxser/utility - # make install - - 8. Make special file + correct position. + g. If you use 'lilo' utility, you should check /etc/lilo.conf + 'image' item specified the path which is the 'vmlinuz' path, + or you will load wrong (or old) boot kernel image (vmlinuz). + After checking /etc/lilo.conf, please run "lilo". + + Note that if the result of "make bzImage" is ERROR, then you have to + go back to Linux configuration Setup. Type "make menuconfig" in + directory /usr/src/linux. + + + 3.5.6 Make tty device and special file # cd /moxa/mxser/driver # ./msmknod - 9. Reboot + 3.5.7 Make utility + # cd /moxa/mxser/utility + # make clean; make install + + 3.5.8 Reboot - 3.5 Custom configuration + + + 3.6 Custom configuration Although this driver already provides you default configuration, you - still can change the device name and major number.The instruction to + still can change the device name and major number. The instruction to change these parameters are shown as below. Change Device name @@ -306,33 +403,37 @@ Content 2 free major numbers for this driver. There are 3 steps to change major numbers. - 1. Find free major numbers + 3.6.1 Find free major numbers In /proc/devices, you may find all the major numbers occupied in the system. Please select 2 major numbers that are available. e.g. 40, 45. - 2. Create special files + 3.6.2 Create special files Run /moxa/mxser/driver/msmknod to create special files with specified major numbers. - 3. Modify driver with new major number + 3.6.3 Modify driver with new major number Run vi to open /moxa/mxser/driver/mxser.c. Locate the line contains "MXSERMAJOR". Change the content as below. #define MXSERMAJOR 40 #define MXSERCUMAJOR 45 - 4. Run # make install in /moxa/mxser/driver. + 3.6.4 Run "make clean; make install" in /moxa/mxser/driver. - 3.6 Verify driver installation + 3.7 Verify driver installation You may refer to /var/log/messages to check the latest status log reported by this driver whenever it's activated. + ----------------------------------------------------------------------------- 4. Utilities There are 3 utilities contained in this driver. They are msdiag, msmon and msterm. These 3 utilities are released in form of source code. They should be compiled into executable file and copied into /usr/bin. + Before using these utilities, please load driver (refer 3.4 & 3.5) and + make sure you had run the "msmknod" utility. + msdiag - Diagnostic -------------------- - This utility provides the function to detect what Moxa Smartio multiport - board exists in the system. + This utility provides the function to display what Moxa Smartio/Industio + board found by driver in the system. msmon - Port Monitoring ----------------------- @@ -353,12 +454,13 @@ Content application, for example, sending AT command to a modem connected to the port or used as a terminal for login purpose. Note that this is only a dumb terminal emulation without handling full screen operation. + ----------------------------------------------------------------------------- 5. Setserial Supported Setserial parameters are listed as below. - uart set UART type(16450-->disable FIFO, 16550A-->enable FIFO) + uart set UART type(16450-->disable FIFO, 16550A-->enable FIFO) close_delay set the amount of time(in 1/100 of a second) that DTR should be kept low while being closed. closing_wait set the amount of time(in 1/100 of a second) that the @@ -366,7 +468,13 @@ Content being closed, before the receiver is disable. spd_hi Use 57.6kb when the application requests 38.4kb. spd_vhi Use 115.2kb when the application requests 38.4kb. + spd_shi Use 230.4kb when the application requests 38.4kb. + spd_warp Use 460.8kb when the application requests 38.4kb. spd_normal Use 38.4kb when the application requests 38.4kb. + spd_cust Use the custom divisor to set the speed when the + application requests 38.4kb. + divisor This option set the custom divison. + baud_base This option set the base baud rate. ----------------------------------------------------------------------------- 6. Troubleshooting @@ -375,8 +483,9 @@ Content possible. If all the possible solutions fail, please contact our technical support team to get more help. - Error msg: More than 4 Moxa Smartio family boards found. Fifth board and - after are ignored. + + Error msg: More than 4 Moxa Smartio/Industio family boards found. Fifth board + and after are ignored. Solution: To avoid this problem, please unplug fifth and after board, because Moxa driver supports up to 4 boards. @@ -384,7 +493,7 @@ Content Error msg: Request_irq fail, IRQ(?) may be conflict with another device. Solution: Other PCI or ISA devices occupy the assigned IRQ. If you are not sure - which device causes the situation,please check /proc/interrupts to find + which device causes the situation, please check /proc/interrupts to find free IRQ and simply change another free IRQ for Moxa board. Error msg: Board #: C1xx Series(CAP=xxx) interrupt number invalid. @@ -397,15 +506,18 @@ Content Moxa ISA board needs an interrupt vector.Please refer to user's manual "Hardware Installation" chapter to set interrupt vector. - Error msg: Couldn't install MOXA Smartio family driver! + Error msg: Couldn't install MOXA Smartio/Industio family driver! Solution: Load Moxa driver fail, the major number may conflict with other devices. - Please refer to previous section 3.5 to change a free major number for + Please refer to previous section 3.7 to change a free major number for Moxa driver. - Error msg: Couldn't install MOXA Smartio family callout driver! + Error msg: Couldn't install MOXA Smartio/Industio family callout driver! Solution: Load Moxa callout driver fail, the callout device major number may - conflict with other devices. Please refer to previous section 3.5 to + conflict with other devices. Please refer to previous section 3.7 to change a free callout device major number for Moxa driver. + + ----------------------------------------------------------------------------- + diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index ea1b70b35793..99514ced82c5 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -59,6 +59,7 @@ Table of Contents p) Freescale Synchronous Serial Interface q) USB EHCI controllers r) MDIO on GPIOs + s) SPI busses VII - Marvell Discovery mv64[345]6x System Controller chips 1) The /system-controller node @@ -1883,6 +1884,62 @@ platforms are moved over to use the flattened-device-tree model. &qe_pio_c 6>; }; + s) SPI (Serial Peripheral Interface) busses + + SPI busses can be described with a node for the SPI master device + and a set of child nodes for each SPI slave on the bus. For this + discussion, it is assumed that the system's SPI controller is in + SPI master mode. This binding does not describe SPI controllers + in slave mode. + + The SPI master node requires the following properties: + - #address-cells - number of cells required to define a chip select + address on the SPI bus. + - #size-cells - should be zero. + - compatible - name of SPI bus controller following generic names + recommended practice. + No other properties are required in the SPI bus node. It is assumed + that a driver for an SPI bus device will understand that it is an SPI bus. + However, the binding does not attempt to define the specific method for + assigning chip select numbers. Since SPI chip select configuration is + flexible and non-standardized, it is left out of this binding with the + assumption that board specific platform code will be used to manage + chip selects. Individual drivers can define additional properties to + support describing the chip select layout. + + SPI slave nodes must be children of the SPI master node and can + contain the following properties. + - reg - (required) chip select address of device. + - compatible - (required) name of SPI device following generic names + recommended practice + - spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz + - spi-cpol - (optional) Empty property indicating device requires + inverse clock polarity (CPOL) mode + - spi-cpha - (optional) Empty property indicating device requires + shifted clock phase (CPHA) mode + + SPI example for an MPC5200 SPI bus: + spi@f00 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "fsl,mpc5200b-spi","fsl,mpc5200-spi"; + reg = <0xf00 0x20>; + interrupts = <2 13 0 2 14 0>; + interrupt-parent = <&mpc5200_pic>; + + ethernet-switch@0 { + compatible = "micrel,ks8995m"; + spi-max-frequency = <1000000>; + reg = <0>; + }; + + codec@1 { + compatible = "ti,tlv320aic26"; + spi-max-frequency = <100000>; + reg = <1>; + }; + }; + VII - Marvell Discovery mv64[345]6x System Controller chips =========================================================== diff --git a/Documentation/unaligned-memory-access.txt b/Documentation/unaligned-memory-access.txt index b0472ac5226a..f866c72291bf 100644 --- a/Documentation/unaligned-memory-access.txt +++ b/Documentation/unaligned-memory-access.txt @@ -218,9 +218,35 @@ If use of such macros is not convenient, another option is to use memcpy(), where the source or destination (or both) are of type u8* or unsigned char*. Due to the byte-wise nature of this operation, unaligned accesses are avoided. + +Alignment vs. Networking +======================== + +On architectures that require aligned loads, networking requires that the IP +header is aligned on a four-byte boundary to optimise the IP stack. For +regular ethernet hardware, the constant NET_IP_ALIGN is used. On most +architectures this constant has the value 2 because the normal ethernet +header is 14 bytes long, so in order to get proper alignment one needs to +DMA to an address which can be expressed as 4*n + 2. One notable exception +here is powerpc which defines NET_IP_ALIGN to 0 because DMA to unaligned +addresses can be very expensive and dwarf the cost of unaligned loads. + +For some ethernet hardware that cannot DMA to unaligned addresses like +4*n+2 or non-ethernet hardware, this can be a problem, and it is then +required to copy the incoming frame into an aligned buffer. Because this is +unnecessary on architectures that can do unaligned accesses, the code can be +made dependent on CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS like so: + +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS + skb = original skb +#else + skb = copy skb +#endif + -- -Author: Daniel Drake <dsd@gentoo.org> +Authors: Daniel Drake <dsd@gentoo.org>, + Johannes Berg <johannes@sipsolutions.net> With help from: Alan Cox, Avuton Olrich, Heikki Orsila, Jan Engelhardt, -Johannes Berg, Kyle McMartin, Kyle Moffett, Randy Dunlap, Robert Hancock, -Uli Kunitz, Vadim Lobanov +Kyle McMartin, Kyle Moffett, Randy Dunlap, Robert Hancock, Uli Kunitz, +Vadim Lobanov |