Re: [libvirt] [PATCH] domcaps: Check for architecture more wisely

On 08.04.2015 17:25, Cole Robinson wrote: > On 04/08/2015 11:12 AM, Michal Privoznik wrote: >> https://bugzilla.redhat.com/show_bug.cgi?id=1209948 >> >> So we have this bug. The virConnectGetDomainCapabilities() API >> performs a couple of checks before it produces any result. One of >> the checks is if the architecture requested by user can be run by >> the binary (again user provided). However, the check is pretty >> dumb. It merely compares if the default binary architecture >> matches the one provided by user. However, a qemu binary can run >> multiple architectures. For instance: qemu-system-ppc64 can run: >> ppc, ppcle, ppc64, ppc64le and ppcemb. The default is ppc64, so >> if user requested something else, like ppc64le, the check would >> have failed without obvious reason. >> >> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >> --- >> src/qemu/qemu_driver.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c >> index 921417c..d217481 100644 >> --- a/src/qemu/qemu_driver.c >> +++ b/src/qemu/qemu_driver.c >> @@ -18788,7 +18788,10 @@ qemuConnectGetDomainCapabilities(virConnectPtr conn, >> arch_from_caps = virQEMUCapsGetArch(qemuCaps); >> >> if (arch_from_caps != arch && >> - (arch_from_caps != VIR_ARCH_X86_64 || arch != VIR_ARCH_I686)) { >> + !((ARCH_IS_X86(arch) && ARCH_IS_X86(arch_from_caps)) || >> + (ARCH_IS_PPC(arch) && ARCH_IS_PPC(arch_from_caps)) || >> + (ARCH_IS_ARM(arch) && ARCH_IS_ARM(arch_from_caps)) || >> + (ARCH_IS_S390(arch) && ARCH_IS_S390(arch_from_caps)))) { >> virReportError(VIR_ERR_INVALID_ARG, >> _("architecture from emulator '%s' doesn't " >> "match given architecture '%s'"), >> > > As I mentioned in the bug, really I think this is more a problem of the > virQEMUCapsCacheLookup* interface. Nowadays we can have the same emulatorbin > map to multiple architectures, and the same architecture provided by multiple > emulators, so CacheLookup* functions that search for only the specified > emulator or only the specified arch are just going to breed more bugs like this. While I understand your concern, qemu is not helping. It is not exporting list of supported architectures for given binary. What I've found is: a) we use 'query-target' command to determine the target architecture for the binary. However, this returns only the default architecture, not a list of all supported architectures. b) There exists 'qemu-system-* -cpu ?', which outputs something like this: x86 athlon QEMU Virtual CPU version 2.2.92 x86 Broadwell Intel Core Processor (Broadwell) The first item looks like an arch. But it's not much of a help either. For example for qemu-system-{i386,x86_64} I get the very same list of supported CPUs. And architectures too. But if I query those two binaries on QMP for their target they produce different results: 'i386' and 'x86_64'. While I agree your approach is better, there's not much we can do unless qemu is more helping. So I see two options: 1) ask qemu devels 2) merge this meanwhile