+++ This bug was initially created as a clone of Bug #1209948 +++

$ sudo virsh domcapabilities --emulatorbin /usr/bin/qemu-system-ppc64 --arch ppc64le
error: failed to get emulator capabilities
error: invalid argument: architecture from emulator 'ppc64' doesn't match given architecture 'ppc64le'

When the capabilities block is:

  <guest>
    <os_type>hvm</os_type>
    <arch name='ppc64le'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-ppc64</emulator>
      <machine canonical='pseries-2.3' maxCpus='255'>pseries</machine>
      <machine maxCpus='1'>ref405ep</machine>
      <machine maxCpus='1'>virtex-ml507</machine>
      <machine maxCpus='32'>ppce500</machine>
      <machine maxCpus='15'>mpc8544ds</machine>
      <machine maxCpus='1'>bamboo</machine>
      <machine maxCpus='1'>g3beige</machine>
      <machine maxCpus='1'>prep</machine>
      <machine maxCpus='255'>pseries-2.1</machine>
      <machine maxCpus='255'>pseries-2.2</machine>
      <machine maxCpus='1'>mac99</machine>
      <machine maxCpus='1'>taihu</machine>
      <domain type='qemu'/>
    </arch>
    <features>
      <cpuselection/>
      <deviceboot/>
      <disksnapshot default='on' toggle='no'/>
    </features>
  </guest>



Given that nowadays we can have the same emulatorbin map to multiple architectures, and the same architecture provided by multiple emulators, I think any use of virQEMUCapsCacheLookup* should be audited since a single arch or emulatorbin is not always sufficient to lookup what is needed.

--- Additional comment from Ján Tomko on 2015-04-08 10:12:52 EDT ---

What's the libvirt version?

This could have been fixed by
commit 0afa6be8153518fad5862da022f63042cb72abbb
Author:     Prerna Saxena <prerna.ibm.com>
AuthorDate: 2015-02-26 08:10:58 -0600
Commit:     Michal Privoznik <mprivozn>
CommitDate: 2015-03-03 10:57:18 +0100

    RNG: Add 'ppc64le' arch and newer pseries-2.* machine types
    
    Acked-by: Ján Tomko <jtomko>
    Signed-off-by: Prerna Saxena <prerna.ibm.com>

git describe: v1.2.13-35-g0afa6be contains: v1.2.14-rc1~293

--- Additional comment from Cole Robinson on 2015-04-08 10:15:41 EDT ---

(In reply to Ján Tomko from comment #1)
> What's the libvirt version?
> 
> This could have been fixed by
> commit 0afa6be8153518fad5862da022f63042cb72abbb
> Author:     Prerna Saxena <prerna.ibm.com>
> AuthorDate: 2015-02-26 08:10:58 -0600
> Commit:     Michal Privoznik <mprivozn>
> CommitDate: 2015-03-03 10:57:18 +0100
> 
>     RNG: Add 'ppc64le' arch and newer pseries-2.* machine types
>     
>     Acked-by: Ján Tomko <jtomko>
>     Signed-off-by: Prerna Saxena <prerna.ibm.com>
> 
> git describe: v1.2.13-35-g0afa6be contains: v1.2.14-rc1~293

Still relevant with libvirt.git. That commit sounds like it's only about domain RNG. This error is a specific error message in qemu_drivers.c domcapabilities implementation

--- Additional comment from Michal Privoznik on 2015-04-08 10:29:08 EDT ---

The problem is here:

qemu_driver.c:18739) qemuConnectGetDomainCapabilities(virConnectPtr conn,
qemu_driver.c:18740)                                  const char *emulatorbin,
qemu_driver.c:18741)                                  const char *arch_str,
qemu_driver.c:18742)                                  const char *machine,
qemu_driver.c:18743)                                  const char *virttype_str,
qemu_driver.c:18744)                                  unsigned int flags)
qemu_driver.c:18745) {


qemu_driver.c:18780) 
qemu_driver.c:18781)     if (emulatorbin) {
qemu_driver.c:18782)         virArch arch_from_caps;
qemu_driver.c:18783) 
qemu_driver.c:18784)         if (!(qemuCaps = virQEMUCapsCacheLookup(driver->qemuCapsCache,
qemu_driver.c:18785)                                                 emulatorbin)))
qemu_driver.c:18786)             goto cleanup;
qemu_driver.c:18787) 
qemu_driver.c:18788)         arch_from_caps = virQEMUCapsGetArch(qemuCaps);
qemu_driver.c:18789) 
qemu_driver.c:18790)         if (arch_from_caps != arch &&
qemu_driver.c:18791)             (arch_from_caps != VIR_ARCH_X86_64 || arch != VIR_ARCH_I686)) {
qemu_driver.c:18792)             virReportError(VIR_ERR_INVALID_ARG,
qemu_driver.c:18793)                            _("architecture from emulator '%s' doesn't "
qemu_driver.c:18794)                              "match given architecture '%s'"),
qemu_driver.c:18795)                            virArchToString(arch_from_caps),
qemu_driver.c:18796)                            virArchToString(arch));
qemu_driver.c:18797)             goto cleanup;
qemu_driver.c:18798)         }
qemu_driver.c:18799)     } else {

The check for arch_from_caps should cope with all the architectures that binary can run. I'm working on a patch.

--- Additional comment from Michal Privoznik on 2015-04-08 11:12:54 EDT ---

Patch proposed upstream:

https://www.redhat.com/archives/libvir-list/2015-April/msg00301.html