From b3afd9ccefe156ab2dee993118fcdba40341f66e Mon Sep 17 00:00:00 2001

From: Adam Jackson <ajax@redhat.com>

Date: Fri, 1 Oct 2021 11:47:21 -0400

Subject: [PATCH xserver] mustard: xfree86: Disable the PCI probe path

RHEL 9 does not support userspace modesetting drivers for Xorg. Ideally

it would only support DRM drivers, but there are some fallback paths

(efifb mainly) that still require fbdev support. Since the primary use

of the PCI probe path is devices _without_ kernel support, we can safely

disable it. And indeed we want to, because there are some devices

(hyperv v1 e.g.) with both a platform and a PCI presentation, which the

PCI probe code fails to handle such that the server fails to start.

Thus: we #if 0 out the PCI probe in xf86CallDriverProbe.

It might be nice if the platform code knew about fbdev devices, but it

does not, and teaching it would be a large change for little benefit

given we do intend to sunset the fbdev path as well. Since the fbdev

path exists solely for cases where we have only the rudimentary firmare

framebuffer, we should only use it if _no_ platform driver is available.

Thus: we only call the legacy probe method if xf86ProbeIgnorePrimary.

Having done this, we need to go back into fbdevhw and undo fc78bcca:

    commit fc78bcca21e767697de6ad4d8e03b6728856f613 (merge-requests/38)

    Author: Adam Jackson <ajax@redhat.com>

    Date:   Wed Oct 10 14:09:11 2018 -0400

    fbdevhw: Refuse to touch PCI devices on the fallback probe path

Which was well intentioned, but given the above changes we know by the

time we're trying to probe fbdev we really do want it, either because of

the above fallback path or because xorg.conf asked for it. In either

case we shouldn't spuriously fail just because it happens to be PCI.

Thus: We if (0) out the code added in fc78bcca.

Any one of the above might be questionable upstream, hence the mustard

nature of this patch.

---

 hw/xfree86/common/xf86Bus.c  | 4 ++--

 hw/xfree86/fbdevhw/fbdevhw.c | 2 +-

 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/xfree86/common/xf86Bus.c b/hw/xfree86/common/xf86Bus.c

index fd144dbe7a..844ce5a890 100644

--- a/hw/xfree86/common/xf86Bus.c

+++ b/hw/xfree86/common/xf86Bus.c

@@ -84,7 +84,7 @@ xf86CallDriverProbe(DriverPtr drv, Bool detect_only)

     }

 #endif

-#ifdef XSERVER_LIBPCIACCESS

+#if 0

     if (!foundScreen && (drv->PciProbe != NULL)) {

         if (xf86DoConfigure && xf86DoConfigurePass1) {

             assert(detect_only);

@@ -96,7 +96,7 @@ xf86CallDriverProbe(DriverPtr drv, Bool detect_only)

         }

     }

 #endif

-    if (!foundScreen && (drv->Probe != NULL)) {

+    if (!foundScreen && xf86ProbeIgnorePrimary && (drv->Probe != NULL)) {

         xf86Msg(X_WARNING, "Falling back to old probe method for %s\n",

                 drv->driverName);

         foundScreen = (*drv->Probe) (drv, (detect_only) ? PROBE_DETECT

diff --git a/hw/xfree86/fbdevhw/fbdevhw.c b/hw/xfree86/fbdevhw/fbdevhw.c

index 3d8b92e669..171038f46d 100644

--- a/hw/xfree86/fbdevhw/fbdevhw.c

+++ b/hw/xfree86/fbdevhw/fbdevhw.c

@@ -330,7 +330,7 @@ fbdev_open(int scrnIndex, const char *dev, char **namep)

     }

     /* only touch non-PCI devices on this path */

-    {

+    if (0) {

         char buf[PATH_MAX];

         char *sysfs_path = NULL;

         char *node = strrchr(dev, '/') + 1;

-- 

2.31.1