This is problematic since the n270 qemu model won't boot a real kernel compiled for that box.
Eduardo Habkost <ehabk...@redhat.com> wrote: >On Fri, Feb 08, 2013 at 10:30:02AM +0100, Borislav Petkov wrote: >> From: Borislav Petkov <b...@suse.de> >> >> The Atom core (cpu name "n270" in QEMU speak) supports MOVBE. This is >> needed when booting 3.8 and later linux kernels built with the MATOM >> target because we require MOVBE in order to boot properly now. >> >> Cc: "H. Peter Anvin" <h...@zytor.com> >> Cc: Richard Henderson <r...@twiddle.net> >> Signed-off-by: Borislav Petkov <b...@suse.de> >> --- >> >> Right, so I was playing with booting MATOM kernels in QEMU. >> As it turns out, QEMU's n270 model doesn't advertize MOVBE >> although the real hardware supports it. Quick search pointed me to >> http://lists.nongnu.org/archive/html/qemu-devel/2013-01/msg04317.html >> which adds that support, among other things. I've merged Richard's >> patchset with qemu's current master and after applying this patch >below, >> I can report success booting an MATOM kernel with QEMU. The same >kernel >> boots on the real n270 hardware, btw. >> >> target-i386/cpu.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/target-i386/cpu.c b/target-i386/cpu.c >> index 9f38e4435e53..83816edd8410 100644 >> --- a/target-i386/cpu.c >> +++ b/target-i386/cpu.c >> @@ -610,7 +610,8 @@ static x86_def_t builtin_x86_defs[] = { >> CPUID_ACPI | CPUID_SS | CPUID_HT | CPUID_TM | CPUID_PBE, >> /* Some CPUs got no CPUID_SEP */ >> .ext_features = CPUID_EXT_SSE3 | CPUID_EXT_MONITOR | >CPUID_EXT_SSSE3 | >> - CPUID_EXT_DSCPL | CPUID_EXT_EST | CPUID_EXT_TM2 | >CPUID_EXT_XTPR, >> + CPUID_EXT_DSCPL | CPUID_EXT_EST | CPUID_EXT_TM2 | >CPUID_EXT_XTPR | >> + CPUID_EXT_MOVBE, >> .ext2_features = (PPRO_FEATURES & CPUID_EXT2_AMD_ALIASES) | > > >"-machine pc-1.3 -cpu n270" (and older machine-types) needs to keep >MOVBE disabled, or you will break live migration. > >Personally I wouldn't mind declaring n270 as a non-migratable CPU >model. >But libvirt supports n270, so it already expects n270 to expose a >stable >ABI on each machine-type. > > >> CPUID_EXT2_NX, >> .ext3_features = CPUID_EXT3_LAHF_LM, >> -- >> 1.8.1.2.422.g08c0e7f >> >> -- Sent from my mobile phone. Please excuse brevity and lack of formatting.
