> Date: Mon, 8 Jun 2020 13:28:55 +0200
> From: Christian Weisgerber <na...@mips.inka.de>
>
> powerpc has byte-swapping 16 and 32-bit load/stores and we use those
> in <machine/endian.h>.
>
> Starting with POWER7 (Power ISA v.2.06), there are also corresponding
> 64-bit instructions. Do we want to use those on powerpc64? Or do
> we want to keep compatibility with older processors?
There is an interest in supporting PowerPC 970 ("G5"). That would
allow people to use more than 2G of RAM on the last generations of
Apple PowerMac machines. Otherwise I don't think we are interested in
anything before POWER8.
That said, I don't think the 64-bit bteswapping operations are used
very much in our kernel. Seo the benefit of this may be small. But
then a diff like this can be reversed without too much fuss.
ok kettenis@
> Index: arch/powerpc64/include/endian.h
> ===================================================================
> RCS file: /cvs/src/sys/arch/powerpc64/include/endian.h,v
> retrieving revision 1.1
> diff -u -p -r1.1 endian.h
> --- arch/powerpc64/include/endian.h 16 May 2020 17:11:14 -0000 1.1
> +++ arch/powerpc64/include/endian.h 8 Jun 2020 11:16:33 -0000
> @@ -36,7 +36,7 @@ __mswap16(volatile const __uint16_t *m)
>
> __asm("lhbrx %0, 0, %1"
> : "=r" (v)
> - : "r" (m), "m" (*m));
> + : "r" (m), "m" (*m));
>
> return (v);
> }
> @@ -48,7 +48,7 @@ __mswap32(volatile const __uint32_t *m)
>
> __asm("lwbrx %0, 0, %1"
> : "=r" (v)
> - : "r" (m), "m" (*m));
> + : "r" (m), "m" (*m));
>
> return (v);
> }
> @@ -56,11 +56,11 @@ __mswap32(volatile const __uint32_t *m)
> static inline __uint64_t
> __mswap64(volatile const __uint64_t *m)
> {
> - __uint32_t *a = (__uint32_t *)m;
> __uint64_t v;
>
> - v = (__uint64_t)__mswap32(a + 1) << 32 |
> - (__uint64_t)__mswap32(a);
> + __asm("ldbrx %0, 0, %1"
> + : "=r" (v)
> + : "r" (m), "m" (*m));
>
> return (v);
> }
> @@ -84,10 +84,9 @@ __swapm32(volatile __uint32_t *m, __uint
> static inline void
> __swapm64(volatile __uint64_t *m, __uint64_t v)
> {
> - __uint32_t *a = (__uint32_t *)m;
> -
> - __swapm32(a + 1, v >> 32);
> - __swapm32(a, v);
> + __asm("stdbrx %1, 0, %2"
> + : "=m" (*m)
> + : "r" (v), "r" (m));
> }
>
> #define __HAVE_MD_SWAPIO
> --
> Christian "naddy" Weisgerber na...@mips.inka.de
>
>
