On 04/25/2013 02:39 AM, Eric Blake wrote:
> On 04/23/2013 06:47 AM, Ján Tomko wrote:
>> @@ -1326,15 +1368,53 @@ qemuDomainAssignPCIAddresses(virDomainDefPtr def,
>> qemuDomainObjPrivatePtr priv = NULL;
>>
>> if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
>> + int max_idx = -1;
>
> So let's trace what happens if I have XML with no <controller> but I do
> use 33 PCI devices and have a capable qemu:
>
> max_idx starts at -1,
>
>> int nbuses = 0;
>> int i;
>> + int rv;
>>
>> for (i = 0; i < def->ncontrollers; i++) {
>> - if (def->controllers[i]->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI)
>> - nbuses++;
>> + if (def->controllers[i]->type ==
>> VIR_DOMAIN_CONTROLLER_TYPE_PCI) {
>> + if (def->controllers[i]->idx > max_idx)
>> + max_idx = def->controllers[i]->idx;
>> + }
>> + }
>
> If no controllers were specified, it is still at -1,
>
>> +
>> + nbuses = max_idx + 1;
>
> so nbuses is now 0,
>
>> +
>> + if (nbuses > 0 &&
>> + virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_PCI_BRIDGE)) {
>
> therefore we skip this if,
>
>> + virDomainDeviceInfo info;
>> + /* 1st pass to figure out how many PCI bridges we need */
>> + if (!(addrs = qemuDomainPCIAddressSetCreate(def, nbuses, true)))
>> + goto cleanup;
>> + if (qemuAssignDevicePCISlots(def, qemuCaps, addrs) < 0)
>> + goto cleanup;
>> + /* Reserve 1 extra slot for a (potential) bridge */
>> + if (qemuDomainPCIAddressSetNextAddr(addrs, &info) < 0)
>> + goto cleanup;
>> +
>> + for (i = 1; i < addrs->nbuses; i++) {
>> + if ((rv = virDomainDefMaybeAddController(
>> + def, VIR_DOMAIN_CONTROLLER_TYPE_PCI,
>> + i, VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE)) < 0)
>> + goto cleanup;
>> + /* If we added a new bridge, we will need one more address
>> */
>> + if (rv > 0 && qemuDomainPCIAddressSetNextAddr(addrs, &info)
>> < 0)
>> + goto cleanup;
>> + }
>> + nbuses = addrs->nbuses;
>> + qemuDomainPCIAddressSetFree(addrs);
>> + addrs = NULL;
>> +
>> + } else if (max_idx > 0) {
>
> we don't error out,
>
>> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> + _("PCI bridges are not supported "
>> + "by this QEMU binary"));
>> + goto cleanup;
>> }
>
> but we also didn't auto-instantiate any bridges, even if the capability
> is supported. Is that a problem?
No, if the machine has no buses, we would have no place to put the
bridge in. (Unless it's a PCI express machine, but libvirt doesn't know
how to use those yet)
And we'll error out anyway with:
error: XML error: No PCI buses available
either in GetNextSlot called by AssignPCISlots for devices without an
address, or in PCIAddressValidate called by CollectPCIAddress for
explicitly specified PCI addresses.
Jan
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