[libvirt] [PATCH] qemu: x86_64 is good enough for i686

[Martin Kletzander]

On Thu, Oct 16, 2014 at 09:28:00PM +0200, Lubomir Rintel wrote:
>virt-manager on Fedora sets up i686 hosts with "/usr/bin/qemu-kvm" emulator,
>which in turn unconditionally execs qemu-system-x86_64 querying capabilities
>then fails:
>
>Error launching details: invalid argument: architecture from emulator 'x86_64' doesn't match given architecture 'i686'
>
>Traceback (most recent call last):
>  File "/usr/share/virt-manager/virtManager/engine.py", line 748, in _show_vm_helper
>    details = self._get_details_dialog(uri, vm.get_connkey())
>  File "/usr/share/virt-manager/virtManager/engine.py", line 726, in _get_details_dialog
>    obj = vmmDetails(conn.get_vm(connkey))
>  File "/usr/share/virt-manager/virtManager/details.py", line 399, in __init__
>    self.init_details()
>  File "/usr/share/virt-manager/virtManager/details.py", line 784, in init_details
>    domcaps = self.vm.get_domain_capabilities()
>  File "/usr/share/virt-manager/virtManager/domain.py", line 518, in get_domain_capabilities
>    self.get_xmlobj().os.machine, self.get_xmlobj().type)
>  File "/usr/lib/python2.7/site-packages/libvirt.py", line 3492, in getDomainCapabilities
>    if ret is None: raise libvirtError ('virConnectGetDomainCapabilities() failed', conn=self)
>libvirtError: invalid argument: architecture from emulator 'x86_64' doesn't match given architecture 'i686'
>
>Journal:
>
>Oct 16 21:08:26 goatlord.localdomain libvirtd[1530]: invalid argument: architecture from emulator 'x86_64' doesn't match given architecture 'i686'
>---
> src/qemu/qemu_driver.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>index 7377320..e4b2b6c 100644
>--- a/src/qemu/qemu_driver.c
>+++ b/src/qemu/qemu_driver.c
>@@ -17809,7 +17809,8 @@ qemuConnectGetDomainCapabilities(virConnectPtr conn,
>
>         arch_from_caps = virQEMUCapsGetArch(qemuCaps);
>
>-        if (arch_from_caps != arch) {
>+        if (arch_from_caps != arch &&
>+	    (arch_from_caps != VIR_ARCH_X86_64 || arch != VIR_ARCH_I686)) {

You haven't ran make syntax-check, otherwise it would tell you there's
tab with 4 spaces after that and we use spaces only.

It would be nice to add a test case for this particular case.  Anyway
ACK, I'll push it in a while with that line fixed.

However, I wonder if we only limit the 32/64 bit machines by the
processor, because it looks like one can run even the following
combination:

  qemu-system-i686 -cpu Haswell

And this is even with <type arch='x86_64' machine='pc-q35-2.2'>!  Is
this still 64bit cpu running in 32bit mode?

Martin
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