Nadav Amit <namit@xxxxxxxxxx> writes: > On Oct 3, 2022, at 8:03 AM, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote: > >> Not my but rather PCI maintainer's call but IMHO dropping 'const' is >> better, introducing a new global var is our 'last resort' and should be >> avoided whenever possible. Alternatively, you can add a >> raw_pci_ext_ops_preferred() function checking somethin within 'struct >> hypervisor_x86' but I'm unsure if it's better. >> >> Also, please check Alex' question/suggestion. > > Here is my take (and Ajay knows probably more than me): > > Looking briefly on MCFG, I do not see a clean way of using the ACPI table. > The two options are either to use a reserved field (which who knows, might > be used one day) or some OEM ID. I am also not familiar with > PCI_COMMAND.MEMORY=0, so Ajay can hopefully give some answer about that. > > Anyhow, I understand (although not relate) to the objection for a new global > variable. How about explicitly calling this hardware bug a “bug” and using > the proper infrastructure? Calling it explicitly a bug may even push whoever > can to resolve it. > > IOW, how about doing something along the lines of (not tested): > Works for me. Going forward, the intention shoud be to also clear the bug on other x86 hypervisors, e.g. we test modern Hyper-V versions and if MMIO works well we clear it, we test modern QEMU/KVM setups and if MMIO works introduce a feature bit somewhere and also clear the bug in the guest when the bit is set. -- Vitaly
