Messages in this thread | | | Subject | Re: [PATCH v2] powerpc32: memcpy/memset: only use dcbz once cache is enabled | From | christophe leroy <> | Date | Sat, 12 Sep 2015 11:57:21 +0200 |
| |
Le 11/09/2015 03:24, Michael Ellerman a écrit : > On Thu, 2015-09-10 at 17:05 -0500, Scott Wood wrote: >> >> I don't think this duplication is what Michael meant by "the normal cpu >> feature sections". What else is going to use this very specific >> infrastructure? > Yeah, sorry, I was hoping you could do it with the existing cpu feature > mechanism. > > It looks like the timing doesn't work, ie. you need to patch this stuff in > machine_init(), which is later than the regular patching which gets done in > early_init(). > > This is one of the festering differences we have between the 32 and 64-bit > initialisation code, ie. on 64-bit we do the patching much later. > >
I've just thought about maybe another alternative. Is there any issue with calling do_feature_fixups() twice for the same features ? If not, we could define a MMU_CACHE_NOW_ON dummy MMU feature, then call again do_feature_fixups() in machine_init() to patch memcpy/memset stuff, something like:
In arch/powerpc/include/asm/mmu.h: +#define MMU_CACHE_NOW_ON ASM_CONST(0x00008000)
In arch/powerpc/kernel/setup_32.c: @machine_init()
udbg_early_init();
+ spec = identify_cpu(0, mfspr(SPRN_PVR)); + do_feature_fixups(spec->mmu_features | MMU_CACHE_NOW_ON, + &__start___mmu_ftr_fixup, + &__stop___mmu_ftr_fixup);
/* Do some early initialization based on the flat device tree */ early_init_devtree(__va(dt_ptr));
Christophe
--- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. https://www.avast.com/antivirus
| |