Hi, all
On 11.10.21 16:40, Bertrand Marquis wrote: > Hi Roger, > > + Oleksandr to have a better PCI expert then me. > >> On 11 Oct 2021, at 14:20, Roger Pau Monné <roger....@citrix.com> wrote: >> >> On Mon, Oct 11, 2021 at 12:11:04PM +0000, Bertrand Marquis wrote: >>> Hi Roger, >>> >>>> On 11 Oct 2021, at 12:47, Roger Pau Monné <roger....@citrix.com> wrote: >>>> >>>> On Wed, Oct 06, 2021 at 06:40:27PM +0100, Rahul Singh wrote: >>>>> ARM architecture does not implement I/O ports. Ignore this call on ARM >>>>> to avoid the overhead of making a hypercall just for Xen to return >>>>> -ENOSYS. >>>> What is the cal trace of this function actually on Arm? >>>> >>>> AFAICT libxl will only call xc_domain_ioport_permission if there are >>>> IO ports explicitly defined in the guest configuration, or if any of >>>> the BARs of the PCI device is in the IO space, which is not possible >>>> on Arm. >>> PCI devices BARs can be in the IO space as the PCI devices are not >>> Arm specific. There is not ioports on arm so to be used those can be >>> in some cases remapped and accessed as MMIOs or are not possible >>> to use at all. >>> >>> But the IO space does appear when BARs are listed even on Arm. >> Urg, I wonder whether those devices with IO BARs will work correctly >> under Arm then. >> >> How do you know whether the BAR has been remapped from IO space into >> MMIO? > We cannot, I think the platform will define if this is the case and where. > @oleksandr: I remember that this was discussed during some of our > meetings but I have no idea of the details here, can you help ? > For the guest domains we emulate a host bridge without IO, so the guest won't be able to assign any IO memory at all.
