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>
> ---
> 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?
--
Eduardo