Paul Mackerras <pau...@samba.org> writes: > On Mon, Jul 09, 2012 at 06:43:41PM +0530, Aneesh Kumar K.V wrote: >> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> >> >> Increase max addressable range to 64TB. This is not tested on >> real hardware yet. >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> >> --- >> arch/powerpc/include/asm/mmu-hash64.h | 8 ++++---- >> arch/powerpc/include/asm/pgtable-ppc64-4k.h | 2 +- >> arch/powerpc/include/asm/pgtable-ppc64-64k.h | 2 +- >> arch/powerpc/include/asm/processor.h | 4 ++-- >> arch/powerpc/include/asm/sparsemem.h | 4 ++-- >> 5 files changed, 10 insertions(+), 10 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/mmu-hash64.h >> b/arch/powerpc/include/asm/mmu-hash64.h >> index aa0d560..a227ba7 100644 >> --- a/arch/powerpc/include/asm/mmu-hash64.h >> +++ b/arch/powerpc/include/asm/mmu-hash64.h >> @@ -374,16 +374,16 @@ extern void slb_set_size(u16 size); >> */ >> >> #define VSID_MULTIPLIER_256M ASM_CONST(200730139) /* 28-bit prime >> */ >> -#define VSID_BITS_256M 36 >> +#define VSID_BITS_256M 38 >> #define VSID_MODULUS_256M ((1UL<<VSID_BITS_256M)-1) > > With these settings, the multiplication in ASM_VSID_SCRAMBLE could > overflow, leading to incorrect results (which would cause occasional > corruption of user processes under heavy load). You will need to > reduce the multiplier to be less than 2^26, and it will need to be > co-prime with 2^38 - 1. (Probably, the same value as we use in the 1T > case would be OK.)
I ended up using the same value as VSID_MULTIPLIER_1T. (gdb) p/d 1ull << 38 $1 = 274877906944 (gdb) p/d 274877906943/12538073 $2 = 21923 (gdb) p/d 12538073ll*21923 $5 = 274872174379 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
