| Message ID | 20220720064234.93576-1-heinrich.schuchardt@canonical.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | [1/1] docs: pcie: describe PCIe option ROMs | expand |
On 7/20/22 08:42, Heinrich Schuchardt wrote: > Provide a descriptions of the options that control the emulation of option > ROMS for PCIe devices. > > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> > --- > docs/pcie.txt | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/docs/pcie.txt b/docs/pcie.txt > index 89e3502075..a22c1f69f7 100644 > --- a/docs/pcie.txt > +++ b/docs/pcie.txt > @@ -292,6 +292,31 @@ PCI-PCI Bridge slots can be used for legacy PCI host devices. > If you can see the "Express Endpoint" capability in the > output, then the device is indeed PCI Express. > > +8. Option ROM > +============= > +PCIe devices may provide an option ROM. The following properties control the > +emulation of the option ROM: > + > +``rombar`` (default: ``1``) > + Specifies that an option ROM is available. If set to ``0``, no option ROM > + is present. > + > +``romsize`` (default: ``-1``) > + Specifies the size of the option ROM in bytes. The value must be either > + ``-1`` or a power of two. ``-1`` signifies unlimited size. > + > +``romfile`` > + Defines the name of the file to be loaded as option ROM. > + Some devices like virtio-net-pci define a default file name. > + The file size may neither exceed 2 GiB nor ``romsize``. > + > +Some QEMU PCIe devices like virtio-net-pci use an option ROM by default. In the > +following example the option ROM of a virtio-net-pci device is disabled. This > +is useful for architectures where QEMU does not supply an option ROM file. > + > +.. code-block:: console > + > + -device virtio-net-pci,netdev=eth1,mq=on,rombar=0 If no ROM file exists, this is good enough. If it does exist and I create multiple virtio-net-pci devices with rombar=0, I get an error indicating that the same ROM is used twice: qemu-system-riscv64: -device virtio-net-pci,netdev=eth1,mq=on,rombar=0: duplicate fw_cfg file name: genroms/efi-virtio.rom I ended up using to solve the problem: -device virtio-net-pci,netdev=eth1,mq=on,rombar=0,romfile= I guess some input from the maintainers would be helpful here: - Why is the file read if rombar=0? Is this a bug? - Why can't the same option ROM file be used twice? It is read-only. Best regards Heinrich > > 7. Virtio devices > =================
diff --git a/docs/pcie.txt b/docs/pcie.txt index 89e3502075..a22c1f69f7 100644 --- a/docs/pcie.txt +++ b/docs/pcie.txt @@ -292,6 +292,31 @@ PCI-PCI Bridge slots can be used for legacy PCI host devices. If you can see the "Express Endpoint" capability in the output, then the device is indeed PCI Express. +8. Option ROM +============= +PCIe devices may provide an option ROM. The following properties control the +emulation of the option ROM: + +``rombar`` (default: ``1``) + Specifies that an option ROM is available. If set to ``0``, no option ROM + is present. + +``romsize`` (default: ``-1``) + Specifies the size of the option ROM in bytes. The value must be either + ``-1`` or a power of two. ``-1`` signifies unlimited size. + +``romfile`` + Defines the name of the file to be loaded as option ROM. + Some devices like virtio-net-pci define a default file name. + The file size may neither exceed 2 GiB nor ``romsize``. + +Some QEMU PCIe devices like virtio-net-pci use an option ROM by default. In the +following example the option ROM of a virtio-net-pci device is disabled. This +is useful for architectures where QEMU does not supply an option ROM file. + +.. code-block:: console + + -device virtio-net-pci,netdev=eth1,mq=on,rombar=0 7. Virtio devices =================
Provide a descriptions of the options that control the emulation of option ROMS for PCIe devices. Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> --- docs/pcie.txt | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)