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SubjectRe: [PATCH] LoongArch: Clean useless vcsr in loongarch_fpu.
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On 2022/7/4 14:14, huqi wrote:
> From: Qi Hu <huqi@loongson.cn>
>
> The `vcsr` do not use anymore. Remove this member from `loongarch_fpu`.
"The VCSR is not used any more."
>
> Signed-off-by: Qi Hu <huqi@loongson.cn>
> ---
> arch/loongarch/include/asm/fpregdef.h | 1 -
> arch/loongarch/include/asm/processor.h | 2 --
> arch/loongarch/kernel/asm-offsets.c | 1 -
> arch/loongarch/kernel/fpu.S | 10 ----------
> 4 files changed, 14 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/fpregdef.h b/arch/loongarch/include/asm/fpregdef.h
> index adb16e4b43b0..b6be527831dd 100644
> --- a/arch/loongarch/include/asm/fpregdef.h
> +++ b/arch/loongarch/include/asm/fpregdef.h
> @@ -48,6 +48,5 @@
> #define fcsr1 $r1
> #define fcsr2 $r2
> #define fcsr3 $r3
> -#define vcsr16 $r16
>
> #endif /* _ASM_FPREGDEF_H */
> diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
> index 1d63c934b289..57ec45aa078e 100644
> --- a/arch/loongarch/include/asm/processor.h
> +++ b/arch/loongarch/include/asm/processor.h
> @@ -80,7 +80,6 @@ BUILD_FPR_ACCESS(64)
>
> struct loongarch_fpu {
> unsigned int fcsr;
> - unsigned int vcsr;
> uint64_t fcc; /* 8x8 */
> union fpureg fpr[NUM_FPU_REGS];
> };
> @@ -161,7 +160,6 @@ struct thread_struct {
> */ \
> .fpu = { \
> .fcsr = 0, \
> - .vcsr = 0, \
> .fcc = 0, \
> .fpr = {{{0,},},}, \
> }, \
> diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
> index bfb65eb2844f..20cd9e16a95a 100644
> --- a/arch/loongarch/kernel/asm-offsets.c
> +++ b/arch/loongarch/kernel/asm-offsets.c
> @@ -166,7 +166,6 @@ void output_thread_fpu_defines(void)
>
> OFFSET(THREAD_FCSR, loongarch_fpu, fcsr);
> OFFSET(THREAD_FCC, loongarch_fpu, fcc);
> - OFFSET(THREAD_VCSR, loongarch_fpu, vcsr);
> BLANK();
> }
>
> diff --git a/arch/loongarch/kernel/fpu.S b/arch/loongarch/kernel/fpu.S
> index 75c6ce0682a2..a631a7137667 100644
> --- a/arch/loongarch/kernel/fpu.S
> +++ b/arch/loongarch/kernel/fpu.S
> @@ -146,16 +146,6 @@
> movgr2fcsr fcsr0, \tmp0
> .endm
>
> - .macro sc_save_vcsr base, tmp0
> - movfcsr2gr \tmp0, vcsr16
> - EX st.w \tmp0, \base, 0
> - .endm
> -
> - .macro sc_restore_vcsr base, tmp0
> - EX ld.w \tmp0, \base, 0
> - movgr2fcsr vcsr16, \tmp0
> - .endm
> -
> /*
> * Save a thread's fp context.
> */

The original code was written with future LSX/LASX support in mind; the
code is dead currently, but expected to get utilized Soon (TM).

So, I'd like to confirm if future LoongArch models would *not* feature
LSX/LASX in its current form, and that the Loongson Corporation is not
going to upstream LSX/LASX support, given you are apparently a Loongson
employee with the first-hand information? We'd like to avoid code churn
in general, so if the LSX/LASX support is to be eventually mainlined,
removing them now would only lead to them being introduced later.

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