Re: git: 0e33c2e6df7a - main - pci: Only re-route IRQs based on firmware on x86

On 29 Mar 2025, at 20:18, Colin Percival <cperciva@FreeBSD.org> wrote:
> 
> The branch main has been updated by cperciva:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=0e33c2e6df7a5de65db40c7cc0fc97f66da28ccd
> 
> commit 0e33c2e6df7a5de65db40c7cc0fc97f66da28ccd
> Author:     Colin Percival <cperciva@FreeBSD.org>
> AuthorDate: 2025-03-28 18:07:01 +0000
> Commit:     Colin Percival <cperciva@FreeBSD.org>
> CommitDate: 2025-03-29 20:17:29 +0000
> 
>    pci: Only re-route IRQs based on firmware on x86
> 
>    There is a (very historical) call to pci_assign_interrupt for the
>    purpose of routing IRQs which may have been set up wrong by x86 BIOS
>    or firmware.  On non-x86 systems, this is unnecessary; and on INTRNG
>    systems it results in a (synthetic) IRQ leak and ultimately a kernel
>    panic after many hotplug/unplug cycles.

This is in fact incorrect. Whilst there may well be a leak that needs
fixing, the rerouting is absolutely needed on non-x86 platforms. See
5884fab46153dee52bda660bcabca95c3cc97f44 and
7de649170fd804668da78f005c7966941b402106 for some of the history behind
this. As a result of this commit the problem described in the second
commit is reintroduced.

Jess

>    Suggested by:   jhb
>    Reviewed by:    jhb
>    MFC after:      2 weeks
>    Sponsored by:   Amazon
>    Differential Revision:  https://reviews.freebsd.org/D49560
> ---
> sys/dev/pci/pci.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
> index fe99d6beb029..3a51e4c38296 100644
> --- a/sys/dev/pci/pci.c
> +++ b/sys/dev/pci/pci.c
> @@ -4175,6 +4175,7 @@ pci_add_resources(device_t bus, device_t dev, int force, uint32_t prefetchmask)
> if (q->devid == devid && q->type == PCI_QUIRK_MAP_REG)
> pci_add_map(bus, dev, q->arg1, rl, force, 0);
> 
> +#if defined(__i386__) || defined(__amd64__)
> if (cfg->intpin > 0 && PCI_INTERRUPT_VALID(cfg->intline)) {
> /*
> * Try to re-route interrupts. Sometimes the BIOS or
> @@ -4184,6 +4185,7 @@ pci_add_resources(device_t bus, device_t dev, int force, uint32_t prefetchmask)
> */
> pci_assign_interrupt(bus, dev, 1);
> }
> +#endif
> 
> if (pci_usb_takeover && pci_get_class(dev) == PCIC_SERIALBUS &&
>    pci_get_subclass(dev) == PCIS_SERIALBUS_USB) {