Re: [libvirt] [Qemu-devel] [QEMU PATCH 3/3] x86: pc: versioned CPU model names & compatibility aliases

On Thu, Jul 26, 2012 at 12:52:33AM +0200, Andreas Färber wrote: > Am 25.07.2012 20:18, schrieb Eduardo Habkost: >> This adds version number to CPU model names on the "pc-<version>" >> machine-types, so we can create new models with bug fixes while keeping >> compatibility when using older machine-types. >> >> When naming the existing models, I used the last QEMU version where the >> model was changed (see summary below), but by coincidence every single >> one was changed on QEMU-1.1. >> >> - Conroe, Penryn, Nehalem, Opteron_G1, Opteron_G2, Opteron_G3: >> added on 0.13, changed on 1.1 >> - Westmere, SandyBridge, Opteron_G4: added on 1.1 >> >> Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com&gt; >> --- >> hw/pc_piix.c | 56 ++++++++++++++++++++++++++++++++++++ >> sysconfigs/target/cpus-x86_64.conf | 18 ++++++------ >> 2 files changed, 65 insertions(+), 9 deletions(-) >> >> diff --git a/hw/pc_piix.c b/hw/pc_piix.c >> index 0c0096f..ef3840f 100644 >> --- a/hw/pc_piix.c >> +++ b/hw/pc_piix.c >> @@ -349,6 +349,18 @@ static void pc_xen_hvm_init(ram_addr_t ram_size, >> } >> #endif >> >> +/* CPU aliases for pre-1.2 CPU models */ >> +#define V1_1_CPU_ALIASES \ >> + { "Conroe", "Conroe-1.1" }, \ >> + { "Penryn", "Penryn-1.1" }, \ >> + { "Nehalem", "Nehalem-1.1" }, \ >> + { "Westmere", "Westmere-1.1" }, \ >> + { "SandyBridge", "SandyBridge-1.1" }, \ >> + { "Opteron_G1", "Opteron_G1-1.1" }, \ >> + { "Opteron_G2", "Opteron_G2-1.1" }, \ >> + { "Opteron_G3", "Opteron_G3-1.1" }, \ >> + { "Opteron_G4", "Opteron_G4-1.1" }, >> + >> static QEMUMachine pc_machine_v1_2 = { >> .name = "pc-1.2", >> .alias = "pc", >> @@ -356,6 +368,10 @@ static QEMUMachine pc_machine_v1_2 = { >> .init = pc_init_pci, >> .max_cpus = 255, >> .is_default = 1, >> + .cpu_aliases = (CPUModelAlias[]) { >> + V1_1_CPU_ALIASES >> + {NULL, NULL}, >> + }, >> }; >> >> #define PC_COMPAT_1_1 \ > [...] >> diff --git a/sysconfigs/target/cpus-x86_64.conf b/sysconfigs/target/cpus-x86_64.conf >> index cee0ea9..14c7891 100644 >> --- a/sysconfigs/target/cpus-x86_64.conf >> +++ b/sysconfigs/target/cpus-x86_64.conf >> @@ -1,7 +1,7 @@ >> # x86 CPU MODELS >> >> [cpudef] >> - name = "Conroe" >> + name = "Conroe-1.1" >> level = "2" >> vendor = "GenuineIntel" >> family = "6" > [snip] > > So where are the actual differences between, e.g., Conroe-1.1 and > Conroe? I'd expect we need either an additional string applying > parameter presets such as maybe "x2apic=off" or a nested list of > (property, value) pairs. There are no differences yet, until we make updates in the Conroe model. If we have to make any change (to fix a bug, for example), we would create a "Conroe-1.2" CPU model, and make the "pc-1.2" machine-type alias "Conroe" to "Conroe-1.2" while keeping the older machine-types using "Conroe-1.1". > > As long as there's no concept for actually modelling versioned CPUs, I > consider this RFC stage and not worth merging yet... What do you mean by "no concept for actually modelling versioned CPUs"? You mean there's no use-case or reason for versioning them, or that the series don't model the versioning properly?