On 22/04/2024 13:36, Conor Dooley wrote:
On Mon, Apr 22, 2024 at 01:14:26PM +0200, Clément Léger wrote:
On 22/04/2024 11:35, Conor Dooley wrote:
On Mon, Apr 22, 2024 at 10:53:10AM +0200, Clément Léger wrote:
On 19/04/2024 17:51, Conor Dooley wrote:
On Thu, Apr 18, 2024 at 02:42:27PM +0200, Clément Léger wrote:
The Zc* standard extension for code reduction introduces new extensions. This patch adds support for Zca, Zcf, Zcd and Zcb. Zce, Zcmt and Zcmp are left out of this patch since they are targeting microcontrollers/ embedded CPUs instead of application processors.
Signed-off-by: Clément Léger cleger@rivosinc.com
arch/riscv/include/asm/hwcap.h | 4 ++++ arch/riscv/kernel/cpufeature.c | 4 ++++ 2 files changed, 8 insertions(+)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index 543e3ea2da0e..b7551bad341b 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -82,6 +82,10 @@ #define RISCV_ISA_EXT_ZACAS 73 #define RISCV_ISA_EXT_XANDESPMU 74 #define RISCV_ISA_EXT_ZIMOP 75 +#define RISCV_ISA_EXT_ZCA 76 +#define RISCV_ISA_EXT_ZCB 77 +#define RISCV_ISA_EXT_ZCD 78 +#define RISCV_ISA_EXT_ZCF 79 #define RISCV_ISA_EXT_XLINUXENVCFG 127 diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 115ba001f1bc..09dee071274d 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -261,6 +261,10 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = { __RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA), __RISCV_ISA_EXT_DATA(zfh, RISCV_ISA_EXT_ZFH), __RISCV_ISA_EXT_DATA(zfhmin, RISCV_ISA_EXT_ZFHMIN),
- __RISCV_ISA_EXT_DATA(zca, RISCV_ISA_EXT_ZCA),
- __RISCV_ISA_EXT_DATA(zcb, RISCV_ISA_EXT_ZCB),
- __RISCV_ISA_EXT_DATA(zcd, RISCV_ISA_EXT_ZCD),
- __RISCV_ISA_EXT_DATA(zcf, RISCV_ISA_EXT_ZCF), __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA), __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB), __RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
Ye, this looks exactly like what I "feared".
Ok but for instance, Qemu actually set Zc* based on C/F/D. So the ISA string containing theses dependencies should actually also be allowed. So should we simply ignore them in the ISA string and always do our own "post-processing" based on C/F/D?
I'm not familiar with the contents of all of these extensions, but I assume the reasoning for splitting them out is that you can implement them but not maybe not implement C (or something similar)? If that's the case, you cannot always imply.
Yeah, they can be implemented independently so we need to be able to parse them independently.
However, the kernel currently requires C
No it doesn't! There's a Kconfig option that controls whether or not we build with compressed instructions.
Acked, missed that. That is then advocating to keep separate Zc* extensions.
so we should always have Zca/Zcf/Zcd. But if that changes in the future, then, that won't be true anymore. Better keep it generic probably