*** PATCHES 1 and 2 MAY BE 4.9 MATERIAL *** Alan Cox pointed out that the 486 isn't the only supported CPU that doesn't have CPUID. Let's clean up the mess and make everything faster while we're at it.
Patch 1 is intended to be an easy fix: it makes sync_core() work without CPUID on all 32-bit kernels. It should be quite safe. This will have a negligible performance cost during boot on kernels built for newer CPUs. With this in place, patch 2 reverts the buggy 486 check I added. Patches 3-4 are meant to improve the situation. Patch 3 cleans up the Intel microcode loader and the patch 4 (which depends on patch 3 to work correctly) stops using CPUID in sync_core() altogether. Changes from v3: - Improve sync_core() comments. - Tidy up sync_core() asm. Changes from v2: - Switch to IRET-to-self and get rid of all the paravirt code. - Further immprove the sync_core() comment. Changes from v1: - Fix Xen - Add timing info to the changelog (hint: 2x speedup) - Document patch 1 a bit better. Andy Lutomirski (4): x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" x86/microcode/intel: Replace sync_core() with native_cpuid() x86/asm: Rewrite sync_core() to use IRET-to-self arch/x86/boot/cpu.c | 6 --- arch/x86/include/asm/processor.h | 80 +++++++++++++++++++++++++---------- arch/x86/kernel/cpu/microcode/intel.c | 26 ++++++++++-- 3 files changed, 81 insertions(+), 31 deletions(-) -- 2.9.3 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel