Hi Lukas
Auer, Lukas lukas.auer@aisec.fraunhofer.de 於 2019年1月4日 週五 上午8:40寫道：
Hi Rick,
On Thu, 2019-01-03 at 08:48 +0800, Rick Chen wrote:
Hi Lukas
Auer, Lukas lukas.auer@aisec.fraunhofer.de 於 2019年1月2日 週三 下午8:22寫道：
Hi Rick,
On Wed, 2019-01-02 at 10:54 +0800, Rick Chen wrote:
Hi Lukas
From: Lukas Auer [mailto:lukas.auer@aisec.fraunhofer.de] Sent: Monday, December 31, 2018 2:28 AM To: u-boot@lists.denx.de Cc: Anup Patel; Lukas Auer; Rick Jian-Zhi Chen(陳建志); Bin Meng; Greentime Hu Subject: [PATCH 2/6] riscv: remove invalid dcache flush implementation
The fence instruction is used to enforce device I/O and memory ordering constraints in RISC-V. It does not directly affect the data cache and particular cannot be used to flush or invalidate it. RISC-V does not have instructions for explicit cache control. Remove the flush_dcache_all implementation and its use in all dcache-specific functions in lib/cache.c.
The privileged mention that fence is for the purposes of ordering, but does not say it can not be used to flush or invalidate.
Andes's ax25 have no coherence agent. So it need fence instruction to manipulate cache flush or invalidate. Or there will be some data synchronization error occurs on ae350 platform.
I was not aware of this. Does the ax25 flush the whole dcache on any fence instruction?
Yes. It will flush the whole dcache when execute fence.
You are right, we can't remove it in this case. Since it is specific to the ax25, should I move it into cpu/ax25/cache.c instead?
OK It is good to me. And thanks for your understanding and improvements.
You are welcome! I just submitted version 2 of the patch series.
OK Thanks for your efforts.
B.R Rick
Thanks, Lukas
Regards Rick
Thanks, Lukas
Thanks Rick
This also adds a missing new line between flush_dcache_all and flush_dcache_range in lib/cache.c.
Signed-off-by: Lukas Auer lukas.auer@aisec.fraunhofer.de
This patch only removes the implementation itself and its use in dcache-specific functions in lib/cache.c. There are more uses of it in arch/riscv/, which this patch does not remove.
arch/riscv/lib/cache.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c index ae5c60716f..203e287612 100644 --- a/arch/riscv/lib/cache.c +++ b/arch/riscv/lib/cache.c @@ -13,11 +13,10 @@ void invalidate_icache_all(void)
void flush_dcache_all(void) {
asm volatile ("fence" :::"memory");}
void flush_dcache_range(unsigned long start, unsigned long end) {
flush_dcache_all();}
void invalidate_icache_range(unsigned long start, unsigned long end) @@ -31,7 +30,6 @@ void invalidate_icache_range(unsigned long start, unsigned long end)
void invalidate_dcache_range(unsigned long start, unsigned long end) {
flush_dcache_all();}
void cache_flush(void)
2.20.1