From 1e321fa917fb2d30d39ff1c6ea89d6f1cf4f34a5 Mon Sep 17 00:00:00 2001 From: Leonid Yegoshin Date: Thu, 14 May 2015 18:34:43 -0700 Subject: MIPS64: Support of at least 48 bits of SEGBITS SEGBITS is 40 bits or more, depending on CPU type. Introduces optional support for 48 bits of application virtual address space. Only 16K and 64K pages are supported. Enabling will result in a memory overhead of a small number of pages for small applications. For 64K pages a 3rd level of page tables is required which has some impact during software TLB refill. [ralf@linux-mips.org: Fixed things raised in the review of the version posted and changed kconfig to be a bit more userfriendly.] Signed-off-by: Leonid Yegoshin Cc: aleksey.makarov@auriga.com Cc: james.hogan@imgtec.com Cc: paul.burton@imgtec.com Cc: david.daney@cavium.com Cc: peterz@infradead.org Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: davidlohr@hp.com Cc: kirill@shutemov.name Cc: akpm@linux-foundation.org Cc: mingo@kernel.org Patchwork: https://patchwork.linux-mips.org/patch/10051/ Signed-off-by: Ralf Baechle --- arch/mips/Kconfig | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/mips/Kconfig') diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d5c3621f0dd1..2b7af9014cce 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -2076,6 +2076,16 @@ config KVM_GUEST_TIMER_FREQ emulation when determining guest CPU Frequency. Instead, the guest's timer frequency is specified directly. +config MIPS_VA_BITS_48 + bool "48 bits virtual memory" + depends on 64BIT + help + Support a maximum at least 48 bits of application virtual memory. + Default is 40 bits or less, depending on the CPU. + This option result in a small memory overhead for page tables. + This option is only supported with 16k and 64k page sizes. + If unsure, say N. + choice prompt "Kernel page size" default PAGE_SIZE_4KB @@ -2083,6 +2093,7 @@ choice config PAGE_SIZE_4KB bool "4kB" depends on !CPU_LOONGSON2 && !CPU_LOONGSON3 + depends on !MIPS_VA_BITS_48 help This option select the standard 4kB Linux page size. On some R3000-family processors this is the only available page size. Using @@ -2092,6 +2103,7 @@ config PAGE_SIZE_4KB config PAGE_SIZE_8KB bool "8kB" depends on CPU_R8000 || CPU_CAVIUM_OCTEON + depends on !MIPS_VA_BITS_48 help Using 8kB page size will result in higher performance kernel at the price of higher memory consumption. This option is available @@ -2110,6 +2122,7 @@ config PAGE_SIZE_16KB config PAGE_SIZE_32KB bool "32kB" depends on CPU_CAVIUM_OCTEON + depends on !MIPS_VA_BITS_48 help Using 32kB page size will result in higher performance kernel at the price of higher memory consumption. This option is available -- cgit v1.2.3