From: Benjamin Herrenschmidt Date: Wed, 12 Oct 2005 04:22:50 +0000 (+1000) Subject: [PATCH] ppc32: Tell userland about lack of standard TB X-Git-Tag: v2.6.14-rc5~71 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d8e998c58a870770905495a1d45ebf7285b5b1c5;p=linux-2.6 [PATCH] ppc32: Tell userland about lack of standard TB Glibc is about to get some new high precision timer stuff that relies on the standard timebase of the PPC architecture. However, some (rare & old) CPUs do not have such timebase and it is a bit annoying to have your stuff just crash because you are running on the wrong CPU... This exposes to userland a CPU feature bit that tells that the current processor doesn't have a standard timebase. It's negative logic so that glibc will still "just work" on older kernels (it will just be unhappy on those old CPUs but that doesn't really matter as distro tend to update glibc & kernel at the same time). Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds --- diff --git a/arch/ppc/kernel/cputable.c b/arch/ppc/kernel/cputable.c index 546e1ea4ca..6b76cf58d9 100644 --- a/arch/ppc/kernel/cputable.c +++ b/arch/ppc/kernel/cputable.c @@ -91,7 +91,7 @@ struct cpu_spec cpu_specs[] = { .cpu_features = CPU_FTR_COMMON | CPU_FTR_601 | CPU_FTR_HPTE_TABLE, .cpu_user_features = COMMON_PPC | PPC_FEATURE_601_INSTR | - PPC_FEATURE_UNIFIED_CACHE, + PPC_FEATURE_UNIFIED_CACHE | PPC_FEATURE_NO_TB, .icache_bsize = 32, .dcache_bsize = 32, .cpu_setup = __setup_cpu_601 @@ -745,7 +745,8 @@ struct cpu_spec cpu_specs[] = { .cpu_name = "403GCX", .cpu_features = CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_USE_TB, - .cpu_user_features = PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU, + .cpu_user_features = PPC_FEATURE_32 | + PPC_FEATURE_HAS_MMU | PPC_FEATURE_NO_TB, .icache_bsize = 16, .dcache_bsize = 16, }, diff --git a/include/asm-ppc/cputable.h b/include/asm-ppc/cputable.h index 41d8f8425c..e17c492c87 100644 --- a/include/asm-ppc/cputable.h +++ b/include/asm-ppc/cputable.h @@ -24,6 +24,7 @@ #define PPC_FEATURE_HAS_SPE 0x00800000 #define PPC_FEATURE_HAS_EFP_SINGLE 0x00400000 #define PPC_FEATURE_HAS_EFP_DOUBLE 0x00200000 +#define PPC_FEATURE_NO_TB 0x00100000 #ifdef __KERNEL__