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Date:      Mon, 31 Mar 2025 20:14:38 +0100
From:      Jessica Clarke <jrtc27@freebsd.org>
To:        Colin Percival <cperciva@FreeBSD.org>
Cc:        "src-committers@freebsd.org" <src-committers@FreeBSD.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@FreeBSD.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org>
Subject:   Re: git: 0e33c2e6df7a - main - pci: Only re-route IRQs based on firmware on x86
Message-ID:  <F51D8FD7-4EB5-4EE8-A1AB-867B0FC392CD@freebsd.org>
In-Reply-To: <202503292018.52TKI7va048377@gitrepo.freebsd.org>
References:  <202503292018.52TKI7va048377@gitrepo.freebsd.org>

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On 29 Mar 2025, at 20:18, Colin Percival <cperciva@FreeBSD.org> wrote:
>=20
> The branch main has been updated by cperciva:
>=20
> URL: =
https://cgit.FreeBSD.org/src/commit/?id=3D0e33c2e6df7a5de65db40c7cc0fc97f6=
6da28ccd
>=20
> 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
>=20
>    pci: Only re-route IRQs based on firmware on x86
>=20
>    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(+)
>=20
> 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 =3D=3D devid && q->type =3D=3D PCI_QUIRK_MAP_REG)
> pci_add_map(bus, dev, q->arg1, rl, force, 0);
>=20
> +#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
>=20
> if (pci_usb_takeover && pci_get_class(dev) =3D=3D PCIC_SERIALBUS &&
>    pci_get_subclass(dev) =3D=3D PCIS_SERIALBUS_USB) {




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