Segher Boessenkool <seg...@kernel.crashing.org> writes: > That is a usability problem. Can it be fixed, or will that create its > own compatibility problems? In practice I mean. If it is, the C > libraries could fix it up, for new programs, and then after a while the > kernel can do the sane thing? > > How big is the problem, anyway? Is it only 2.05, or also 2.04, 2.03?
PPC_FEATURE_ARCH_2_05 is the first bit referring to an ISA level. Before that, AT_HWCAP used to have bits for specific processors, e.g. PPC_FEATURE_CELL and PPC_FEATURE_POWER4. Notice that glibc creates its own hwcap-based information that is used by __builtin_cpu_supports(). In this case bits PPC_FEATURE_ARCH_2_05, PPC_FEATURE_POWER5_PLUS, PPC_FEATURE_POWER5 and PPC_FEATURE_POWER4 are enabled whenever if the processor is compatible with the features provided by any of the previous processors [1]. AT_HWCAP and AT_HWCAP2 are kept intact, though. [1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/powerpc/hwcapinfo.c;h=afde05f86382413ce1f0c38e33c9bdd38d6b7e9d;hb=HEAD#l45 -- Tulio Magno
