Am 30.08.2013 21:49, schrieb Eduardo Habkost: > On Fri, Aug 30, 2013 at 04:51:20PM +0200, Andreas Färber wrote: >> Am 27.08.2013 17:24, schrieb Eduardo Habkost: >>> This is an attempt to make the CPUID cache topology code clearer, by >>> replacing the magic numbers in the code with #defines, and moving all >>> the cache information to the same place in the file. >>> >>> I took care of comparing the assembly output of compiling >>> target-i386/cpu.c before and after applying this change, to make sure >>> not a single bit was changed on cpu_x86_cpuid() before and after >>> applying this patch (unfortunately I had to manually check existing >>> differences, because of __LINE__ expansions on >>> object_class_dynamic_cast_assert() calls). >>> >>> This even keeps the code bug-compatible with the previous version: today >>> the cache information returned on AMD cache information leaves (CPUID >>> 0x80000005 & 0x80000006) do not match the information returned on CPUID >>> leaves 2 and 4. The L2 cache information on CPUID leaf 2 also doesn't >>> match the information on CPUID leaf 2. The new constants should make it >>> easier to eventually fix those inconsistencies. All inconsistencies I >>> have found are documented in code comments. >>> >>> Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> >>> Reviewed-by: liguang <lig.f...@cn.fujitsu.com> >>> --- >>> Changes v1 -> v2: >>> * s/leafs/leaves/ on code comments >>> --- >>> target-i386/cpu.c | 184 >>> +++++++++++++++++++++++++++++++++++++++++++++++------- >>> 1 file changed, 162 insertions(+), 22 deletions(-) >> >> I think this is a good idea and the code looked sane, but it is unclear >> to me from v1 whether Li Guang has verified as part of his review that >> all the bits match the original ones or just that Coding Style and >> general idea is okay? >> >> I'm therefore holding off applying this one for today's pull, waiting >> until either someone confirms Eduardo's results or I find the time to do >> so myself, the former being appreciated. :) > > In case anybody wants to verify it: compile it before/after applying the > patch, with: > make CFLAGS='-save-temps -DNDEBUG > and save x86_64-softmmu/cpu.s file from each run. > > You are going to see some differences between both files due to __LINE__ > being used as argument to object*_dynamic_cast_assert(), but nothing > else.
So the only difference I see is movl lines changing slightly before object_dynamic_cast_assert() calls, so I'm applying it to qom-cpu: https://github.com/afaerber/qemu-cpu/commits/qom-cpu (Since for backporting commits I consider it more important to have consistent prefixes, I have shortened the end of the subject instead.) Thanks, Andreas -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
