在 2023/8/9 下午11:03, Richard Henderson 写道:
On 8/9/23 01:26, Jiajie Chen wrote:
LoongArch64-only instructions are marked with regard to the instruction
manual Table 2. LSX instructions are not marked for now for lack of
public manual.
I would expect LSX not to be affected by CPUCFG.1.ARCH, but only by
CPUCFG.2.LSX.
Note that there appears to be a bug with respect to LSX, in that
CPUCFG.2.LSX is not checked. The manual is not clear, but I would
expect CPUCFG.2.LSX == 0 to trigger an illegal instruction exception
before the check for EUEN.SXE == 0 to trigger an instruction disabl > exception. Also, are bit in EUEN allowed to be set to non-zero values
when the corresponding expansion is not present?
No, the kernel always checks for corresponding extensions when setting EUEN.
See enable_fpu/lsx/lasx at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/loongarch/include/asm/fpu.h?h=v6.5-rc5
And, I will send a patch to Check CPUCFG.2.LSX, Thanks for you suggestion.
Thanks.
Song Gao.
