Re: [Qemu-devel] Template for developing a Qe mu device with PCIe and MSI-X

[Adnan Khaleel]

Hi Isaku, thank you very much for your very detailed response. I have a few questions, see below.

Thanks again,

Adnan

> Qemu doesn't support pcie at the moment.
> Only partial patches have been merged, still more patches have to
> be merged for pcie to fully work. The following repo is available.
>
> git clone http://people.valinux.co.jp/~yamahata/qemu/q35/qemu
> git clone http://people.valinux.co.jp/~yamahata/qemu/q35/seabios
> git clone http://people.valinux.co.jp/~yamahata/qemu/q35/vgabios
>
> Note: patched seabios and vgabios are needed, you have to pass ACPI DSDT
> for q35.
> example:
> qemu-system-x86_64 -M pc_q35 -acpitable load_header,data="">
> This repo is for those who want to try/develop pcie support,
> not for upstream merge. So they include patches unsuitable for upstream.
I'm looking at Qemu 0.12.3 and there are 2 files, pci_host.c and pcie_host.c. Can you explain what these do?
Also, I see virtio_pci.c is the only device that uses msi-x in qemu. Can you explain what device this is trying to emulate?
Also, will the support for PCIe be merged with the mail Qemu at some point?
> The repo includes pcie port switch emulator which utilize pcie and
> MSI(not MSI-X).
I guess I could use this as a template for my qemu device mode correct?
> The difference between PCI device and PCIe device is configuration
> space size.
> By setting PCIDeviceInfo::is_express = 1, you'll get 4K configuration
> space. Helper functions for pcie are found in qemu/hw/pcie.c
> For msi-x, see qemu/hw/msix.c.
One last question, does the current implementation allow for 64bit BAR addresses?
> Thanks,
> -- 
> yamahata