diff options
| author | Ard Biesheuvel | 2018-11-07 18:10:38 +0100 |
|---|---|---|
| committer | Catalin Marinas | 2018-11-08 17:50:26 +0000 |
| commit | 26a4676faa1ad5d99317e0cd701e5d6f3e716b77 (patch) | |
| tree | e028f8b341426293dd78072515a6dac5a6c10fc2 /arch | |
| parent | 313a06e636808387822af24c507cba92703568b1 (diff) | |
arm64: mm: define NET_IP_ALIGN to 0
On arm64, there is no need to add 2 bytes of padding to the start of
each network buffer just to make the IP header appear 32-bit aligned.
Since this might actually adversely affect DMA performance some
platforms, let's override NET_IP_ALIGN to 0 to get rid of this
padding.
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/processor.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 3e2091708b8e..6b0d4dff5012 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -24,6 +24,14 @@ #define KERNEL_DS UL(-1) #define USER_DS (TASK_SIZE_64 - 1) +/* + * On arm64 systems, unaligned accesses by the CPU are cheap, and so there is + * no point in shifting all network buffers by 2 bytes just to make some IP + * header fields appear aligned in memory, potentially sacrificing some DMA + * performance on some platforms. + */ +#define NET_IP_ALIGN 0 + #ifndef __ASSEMBLY__ #ifdef __KERNEL__ |