GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC
versions have it.So this patch is to use it for implementing the prefetch.
RISC-V Cache Management Operation instructions has been supported by GCC last
year.you can refer to
https://github.com/gcc-mirror/gcc/commit/3df3ca9014f94fe4af07444fea19b4ab29ba8e73
It is worth noting that CPU based on RISC-V should support Zicbop extension.
This has been already done on other architectures (see the commit:
https://github.com/torvalds/linux/commit/0453fb3c528c5eb3483441a466b24a4cb409eec5).
Signed-off-by: Wang Yang <[email protected]>
---
arch/riscv/include/asm/processor.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index c950a8d9edef..f16d4c85ca5b 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -70,6 +70,17 @@ extern void start_thread(struct pt_regs *regs,
extern unsigned long __get_wchan(struct task_struct *p);
+#define ARCH_HAS_PREFETCH
+static inline void prefetch(const void *ptr)
+{
+ __builtin_prefetch(ptr, 0, 3);
+}
+
+#define ARCH_HAS_PREFETCHW
+static inline void prefetchw(const void *ptr)
+{
+ __builtin_prefetch(ptr, 1, 3);
+}
static inline void wait_for_interrupt(void)
{
--
2.34.1
Hey,
On Wed, Jul 26, 2023 at 03:47:32PM +0800, wang_yang wrote:
> GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC
> versions have it.So this patch is to use it for implementing the prefetch.
>
> RISC-V Cache Management Operation instructions has been supported by GCC last
> year.you can refer to
> https://github.com/gcc-mirror/gcc/commit/3df3ca9014f94fe4af07444fea19b4ab29ba8e73
This should be in a Link: tag.
> It is worth noting that CPU based on RISC-V should support Zicbop extension.
How do you intend determining whether the CPU supports Zicbop?
> This has been already done on other architectures (see the commit:
> https://github.com/torvalds/linux/commit/0453fb3c528c5eb3483441a466b24a4cb409eec5).
That's not how to describe commits, please see how that is done
elsewhere in the git history.
>
> Signed-off-by: Wang Yang <[email protected]>
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#6:
GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC
ERROR: Missing Signed-off-by: line by nominal patch author 'wang_yang <[email protected]>'
> ---
> arch/riscv/include/asm/processor.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index c950a8d9edef..f16d4c85ca5b 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -70,6 +70,17 @@ extern void start_thread(struct pt_regs *regs,
>
> extern unsigned long __get_wchan(struct task_struct *p);
>
> +#define ARCH_HAS_PREFETCH
> +static inline void prefetch(const void *ptr)
> +{
> + __builtin_prefetch(ptr, 0, 3);
As far as I can tell, this does not do anything and will be removed by
the compiler. Please take a look at how other extensions are implemented.
Also, why 3? (Your answer should be in the commit message)
Thanks,
Conor.
> +}
> +
> +#define ARCH_HAS_PREFETCHW
> +static inline void prefetchw(const void *ptr)
> +{
> + __builtin_prefetch(ptr, 1, 3);
> +}
>
> static inline void wait_for_interrupt(void)
> {
> --
> 2.34.1
>