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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt47
1 files changed, 44 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 055284c31e37..3c0646e28488 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -704,8 +704,11 @@
upon panic. This parameter reserves the physical
memory region [offset, offset + size] for that kernel
image. If '@offset' is omitted, then a suitable offset
- is selected automatically. Check
- Documentation/kdump/kdump.txt for further details.
+ is selected automatically.
+ [KNL, x86_64] select a region under 4G first, and
+ fall back to reserve region above 4G when '@offset'
+ hasn't been specified.
+ See Documentation/kdump/kdump.txt for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
@@ -2544,6 +2547,38 @@
in the "bleeding edge" mini2440 support kernel at
http://repo.or.cz/w/linux-2.6/mini2440.git
+ mitigations=
+ [X86,PPC,S390] Control optional mitigations for CPU
+ vulnerabilities. This is a set of curated,
+ arch-independent options, each of which is an
+ aggregation of existing arch-specific options.
+
+ off
+ Disable all optional CPU mitigations. This
+ improves system performance, but it may also
+ expose users to several CPU vulnerabilities.
+ Equivalent to: nopti [X86,PPC]
+ nospectre_v1 [PPC]
+ nobp=0 [S390]
+ nospectre_v2 [X86,PPC,S390]
+ spectre_v2_user=off [X86]
+ spec_store_bypass_disable=off [X86,PPC]
+ l1tf=off [X86]
+
+ auto (default)
+ Mitigate all CPU vulnerabilities, but leave SMT
+ enabled, even if it's vulnerable. This is for
+ users who don't want to be surprised by SMT
+ getting disabled across kernel upgrades, or who
+ have other ways of avoiding SMT-based attacks.
+ Equivalent to: (default behavior)
+
+ auto,nosmt
+ Mitigate all CPU vulnerabilities, disabling SMT
+ if needed. This is for users who always want to
+ be fully mitigated, even if it means losing SMT.
+ Equivalent to: l1tf=flush,nosmt [X86]
+
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
parameter allows control of the logging verbosity for
@@ -3625,7 +3660,9 @@
see CONFIG_RAS_CEC help text.
rcu_nocbs= [KNL]
- The argument is a cpu list, as described above.
+ The argument is a cpu list, as described above,
+ except that the string "all" can be used to
+ specify every CPU on the system.
In kernels built with CONFIG_RCU_NOCB_CPU=y, set
the specified list of CPUs to be no-callback CPUs.
@@ -4705,6 +4742,10 @@
[x86] unstable: mark the TSC clocksource as unstable, this
marks the TSC unconditionally unstable at bootup and
avoids any further wobbles once the TSC watchdog notices.
+ [x86] nowatchdog: disable clocksource watchdog. Used
+ in situations with strict latency requirements (where
+ interruptions from clocksource watchdog are not
+ acceptable).
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface