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| author | Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> | 2015-05-14 18:34:43 -0700 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2016-05-13 14:02:16 +0200 |
| commit | 1e321fa917fb2d30d39ff1c6ea89d6f1cf4f34a5 (patch) | |
| tree | 5262dae1128d52717e3213d5330f7f355d004c52 /arch/mips/Kconfig | |
| parent | 7939469da29a8dfa3947e5d9648d0f0501bc4ba0 (diff) | |
| download | linux-1e321fa917fb2d30d39ff1c6ea89d6f1cf4f34a5.tar.gz linux-1e321fa917fb2d30d39ff1c6ea89d6f1cf4f34a5.tar.xz | |
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 <Leonid.Yegoshin@imgtec.com>
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 <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/Kconfig')
| -rw-r--r-- | arch/mips/Kconfig | 13 |
1 files changed, 13 insertions, 0 deletions
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 |