[PATCH v2 0/2] riscv: improve unaligned memory accesses
Jisheng Zhang
jszhang3 at mail.ustc.edu.cn
Fri Sep 17 07:14:29 PDT 2021
On Thu, 16 Sep 2021 13:08:53 +0000
Chen Huang <chenhuang5 at huawei.com> wrote:
> The patchset improves RISCV unaligned memory accesses, selects
> HAVE_EFFICIENT_UNALIGNED_ACCESS if CPU_HAS_NO_UNALIGNED not
> enabled and supports DCACHE_WORD_ACCESS to improve the efficiency
> of unaligned memory accesses.
>
> If CPU don't support unaligned memory accesses for now, please
> select CONFIG_CPU_HAS_NO_UNALIGNED. For I don't know which CPU
> don't support unaligned memory accesses, I don't choose the
> CONFIG for them.
This will break unified kernel Image for riscv. Obviously, we will have
two images for efficient unaligned access platforms and non-efficient
unaligned access platforms. IMHO, we may need alternative mechanism or
something else to dynamically enable related code path.
Regards
>
> Changes since v1:
> - As Darius Rad and Jisheng Zhang mentioned, some CPUs don't support
> unaligned memory accesses, add an option for CPUs to choose it or not.
>
> Chen Huang (2):
> riscv: support HAVE_EFFICIENT_UNALIGNED_ACCESS
> riscv: Support DCACHE_WORD_ACCESS
>
> arch/riscv/Kconfig | 5 ++++
> arch/riscv/include/asm/word-at-a-time.h | 37 +++++++++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
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