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Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type
From: |
Cole Robinson |
Subject: |
Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type |
Date: |
Mon, 14 Jan 2013 22:45:00 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 |
On 12/12/2012 05:39 PM, Marcelo Tosatti wrote:
>
> To allow migration from qemu-kvm-1.2, where cirrus device has 16 megabytes
> of RAM.
>
> Signed-off-by: Marcelo Tosatti <address@hidden>
>
Hi Marcelo, I'm trying to sort through this again.
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 19e342a..ead4b6b 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -347,6 +347,26 @@ static QEMUMachine pc_machine_v1_2 = {
> },
> };
>
> +#define QEMUKVMPC_COMPAT_1_2 \
> + {\
> + .driver = "cirrus-vga",\
> + .property = "vgamem_mb",\
> + .value = "16",\
> + }
> +
> +static QEMUMachine qemukvmpc_machine_v1_2 = {
> + .name = "qemukvm-pc-1.2",
> + .alias = "pc",
> + .desc = "Standard PC",
> + .init = pc_init_pci,
> + .max_cpus = 255,
> + .compat_props = (GlobalProperty[]) {
> + QEMUKVMPC_COMPAT_1_2,
> + PC_COMPAT_1_2,
> + { /* end of list */ }
> + },
> +};
> +
> #define PC_COMPAT_1_1 \
> PC_COMPAT_1_2,\
> {\
> @@ -645,6 +665,7 @@ static QEMUMachine xenfv_machine = {
>
> static void pc_machine_init(void)
> {
> + qemu_register_machine(&qemukvmpc_machine_v1_2);
> qemu_register_machine(&pc_machine_v1_4);
> qemu_register_machine(&pc_machine_v1_3);
> qemu_register_machine(&pc_machine_v1_2);
>
As previously mentioned in the thread, a back compat machine type doesn't help
us out in Fedora. For the past 3 years all qemu usage in fedora has been using
qemu-kvm.git, so the only incoming migration we care about has to deal with
the qemu-kvm migration incompatibilities.
Libvirt always specifies an explicit machine type and carries it for the life
of the VM. What we want is for 'qemu-kvm-1.2 -M pc-1.2' to migrate seamlessly
into 'qemu-1.3+ -M pc-1.2' without the user or libvirt having to change
machine type.
So what we want to carry in Fedora is:
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index aa3e7f4..b8f5f8a 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -315,6 +315,10 @@ static QEMUMachine pc_machine_v1_3 = {
.driver = "VGA",\
.property = "mmio",\
.value = "off",\
+ },{\
+ .driver = "cirrus-vga",\
+ .property = "vgamem_mb",\
+ .value = stringify(8),\
}
static QEMUMachine pc_machine_v1_2 = {
That sticks the cirrus compat block on the end of PC_COMPAT_1_2, which should
fix cirrus migration from qemu-kvm for all machine types <= pc-1.2. Obviously
this isn't suitable for upstream but we can hide it behind something like
./configure --qemu-kvm-migrate-compat
The other migrate bit is the comment you added to hw/acpi_piix4.c:
/* qemu-kvm 1.2 uses version 3 but advertised as 2
* To support incoming qemu-kvm 1.2 migration, change version_id
* and minimum_version_id to 2 below (which breaks migration from
* qemu 1.2).
*
*/
That's a bit more problematic. Upstream has minimum_version_id=3, so if we
carry version_id=2 in Fedora, our packages will never be able to migrate to an
upstream qemu version, even a VM using pc-1.3 that was added after qemu-kvm
was deprecated.
Is it safe to just set minimum_version_id=2 in qemu.git and be done with it?
It at least doesn't blow up[1] going from qemu-kvm-1.2 -> patched qemu.git,
nor qemu-1.2.2 -> patched qemu.git. But admittedly I don't understand the
subtleties involved in migration compat.
[1] Well, doesn't blow up any more than normal. Migrating stock qemu 1.2.2 ->
qemu.git is crashing for me:
#0 0x00007ffff24b6e50 in __memcmp_sse4_1 () from /lib64/libc.so.6
#1 0x000055555578c532 in patch_hypercalls (s=0x555556513f10)
at /home/crobinso/qemu-clean/hw/i386/../kvmvapic.c:544
#2 vapic_prepare (address@hidden)
at /home/crobinso/qemu-clean/hw/i386/../kvmvapic.c:609
#3 0x000055555578c612 in vapic_post_load (opaque=0x555556513f10,
version_id=<optimized out>)
at /home/crobinso/qemu-clean/hw/i386/../kvmvapic.c:726
#4 0x00005555557ca0b0 in vmstate_load_state (address@hidden, vmsd=
0x555555c0a840 <vmstate_vapic>, opaque=0x555556513f10, version_id=1)
at /home/crobinso/qemu-clean/savevm.c:1451
#5 0x00005555557cac53 in vmstate_load (version_id=<optimized out>, se=
0x555556520da0, f=0x555556636510)
at /home/crobinso/qemu-clean/savevm.c:1514
#6 qemu_loadvm_state (address@hidden)
at /home/crobinso/qemu-clean/savevm.c:1977
#7 0x00005555556fa15e in process_incoming_migration_co (opaque=0x555556636510)
at migration.c:97
#8 0x000055555561f82a in coroutine_trampoline (i0=<optimized out>,
i1=<optimized out>) at coroutine-ucontext.c:138
#9 0x00007ffff23a16c0 in ?? () from /lib64/libc.so.6
#10 0x00007fffffffd270 in ?? ()
#11 0x0000000000000000 in ?? ()
Using:
qemu-system-x86_64 -M pc-1.2 -sdl -net none -vga cirrus -enable-kvm -m 2048
-incoming 'exec:cat migrate-to-file.img'
Thanks,
Cole
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type,
Cole Robinson <=
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Paolo Bonzini, 2013/01/15
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Cole Robinson, 2013/01/16
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Marcelo Tosatti, 2013/01/18
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Cole Robinson, 2013/01/18
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Paolo Bonzini, 2013/01/18
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Marcelo Tosatti, 2013/01/18
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Paolo Bonzini, 2013/01/19
- Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type, Marcelo Tosatti, 2013/01/18