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| author | Kefeng Wang <wangkefeng.wang@huawei.com> | 2023-01-04 21:00:00 +0800 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2023-01-12 16:45:05 +0000 |
| commit | 5a4c2a314083b07751c3151baf5e6ed7cc3aba36 (patch) | |
| tree | 66d3ab121e5282641718e2d36a8f4337c1aa22f5 /arch/arm64/Kconfig | |
| parent | b7bfaa761d760e72a969d116517eaa12e404c262 (diff) | |
| download | linux-stable-5a4c2a314083b07751c3151baf5e6ed7cc3aba36.tar.gz linux-stable-5a4c2a314083b07751c3151baf5e6ed7cc3aba36.tar.bz2 linux-stable-5a4c2a314083b07751c3151baf5e6ed7cc3aba36.zip | |
arm64: make ARCH_FORCE_MAX_ORDER selectable
The other architectures with ARCH_FORCE_MAX_ORDER are selectable,
but not for ARM64, this is to make it selectable on ARM64, which
is useful for user that need to allocate more than 4MB of physically
contiguous memory with 4K pagesize, also bigger on 16K pagesize too, the
max value of MAX_ORDER is calculated bellow,
see include/linux/mmzone.h,
MAX_ORDER - 1 + PAGE_SHIFT <= SECTION_SIZE_BITS
so max value of MAX_ORDER = SECTION_SIZE_BITS + 1 - PAGE_SHIFT
| SECTION_SIZE_BITS | PAGE_SHIFT | max MAX_ORDER | default MAX_ORDER |
----+-------------------+--------------+-----------------+--------------------+
4K | 27 | 12 | 16 | 11 |
16K | 27 | 14 | 14 | 12 |
64K | 29 | 16 | 14 | 14 |
----+-------------------+--------------+-----------------+--------------------+
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Link: https://lore.kernel.org/r/20230104130000.69806-1-wangkefeng.wang@huawei.com
[catalin.marinas@arm.com: add the calculations as comment to arch/arm64/Kconfig]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 03934808b2ed..8cfd8dcf7e75 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1456,10 +1456,23 @@ config XEN help Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64. +# include/linux/mmzone.h requires the following to be true: +# +# MAX_ORDER - 1 + PAGE_SHIFT <= SECTION_SIZE_BITS +# +# so the maximum value of MAX_ORDER is SECTION_SIZE_BITS + 1 - PAGE_SHIFT: +# +# | SECTION_SIZE_BITS | PAGE_SHIFT | max MAX_ORDER | default MAX_ORDER | +# ----+-------------------+--------------+-----------------+--------------------+ +# 4K | 27 | 12 | 16 | 11 | +# 16K | 27 | 14 | 14 | 12 | +# 64K | 29 | 16 | 14 | 14 | config ARCH_FORCE_MAX_ORDER - int + int "Maximum zone order" if ARM64_4K_PAGES || ARM64_16K_PAGES default "14" if ARM64_64K_PAGES + range 12 14 if ARM64_16K_PAGES default "12" if ARM64_16K_PAGES + range 11 16 if ARM64_4K_PAGES default "11" help The kernel memory allocator divides physically contiguous memory |