Allow users to experimentally specify speed and width values for the
generic PCIe root port. Defaults remain at 2.5GT/s & x1 for
compatiblity with the intent to only support changing defaults via
machine types for now.
Note for libvirt testing that pcie-root-port controllers are given
default names like "pci.7" which don't play well with using the
"-set device.$name.$prop=$value" options accessible to us via
<qemu:commandline> options. The solution is to add an <alias> to the
pcie-root-port <controller>, for example:
<controller type='pci' index='7' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='7' port='0x15'/>
<alias name='ua-gfx0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/>
</controller>
The "ua-" here is a mandatory prefix. We can then use:
<qemu:commandline>
<qemu:arg value='-set'/>
<qemu:arg value='device.ua-gfx0.x-speed=8'/>
<qemu:arg value='-set'/>
<qemu:arg value='device.ua-gfx0.x-width=16'/>
</qemu:commandline>
or, without an alias, set globals such as:
<qemu:commandline>
<qemu:arg value='-global'/>
<qemu:arg value='pcie-root-port.x-speed=8'/>
<qemu:arg value='-global'/>
<qemu:arg value='pcie-root-port.x-width=16'/>
</qemu:commandline>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Tested-by: Geoffrey McRae <geoff@hostfission.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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