[libvirt] [PATCH 0/6] auto-assign addresses when <address type='pci'/> is specified
Ján Tomko
jtomko at redhat.com
Fri May 20 06:32:37 UTC 2016
On Thu, May 19, 2016 at 05:14:33PM -0400, Laine Stump wrote:
> On 05/19/2016 01:23 PM, Ján Tomko wrote:
> > Yes, qemu_hotplug.c has a few of those places using == DEVICE_ADDRESS_TYPE_PCI
> > untouched by this series.
>
> Since they happen after parse is finished, it should be safe.
>
> And anyway, looking at those uses, I think what most of them are doing
> (calling virDomainPCIAddressEnsureAddr()) is 100% unnecessary, since
> it's now already done when addresses are assigned in
> qemuDomainDefAssignAddresses(), which has already been called.
Actually, virDomainPCIAddressEnsureAddr is the place where the address
gets assigned. But only when address == NONE or PCI, which is OK because
virDomainPCIAddressEnsureAddr calls PCIAddressIsPresent to decide
whether it needs to allocate a new one.
qemuDomainDefAssignAddresses is only called after parsing the whole
domain, not just one device.
> (Back in
> Jan 2010 when the calls to qemuDomainPCIAddressEnsureAddr() were added
> (commit d8acc4), this was not the case - they were needed in order for
> the new devices to get an address assigned, but a lot has changed since
> then - even before Cole put in the postparse callback address assignment
> stuff and called it when attaching a device, we had already been
> assigning addresses during the higher level qemuDomainAttachDeviceConfig
> for a long time (since commit f5dd58a in June 2012;
qemuDomainAttachDeviceConfig is for changing the persistent definition.
Hotplug in qemuDomainAttachDeviceLive does not call any other address
assignment function.
Jan
> long enough that the
> calls to qemuDomainCCWAddressAssign() that are also sprinkled throughout
> qemu_hotplug.c in the same vicinity as the calls to
> qemuDomainPCIAddressEnsureAddr() weren't needed *even at the time they
> were added!* (commit f94646, March 2013). This was purely cargo-cult
> coding, caused by commit f5dd58a failing to remove the calls to
> ...EnsureAddr(). The interesting bit is that both of these commits were
> put in in support of s390 virtio devices.).
>
> (Well, *that* was a nice trip down git "memory lane" (aka "blame")
>
> So, the result is that most of the code in qemu_hotplug that requires
> checking for address type is unneeded, and I'm going to send a patch to
> remove it.
>
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