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

["Andreas Färber" <afaerber@suse.de>]

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@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.

As long as there's no concept for actually modelling versioned CPUs, I
consider this RFC stage and not worth merging yet...

Regards,
Andreas

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