[Bug 28592] New: When KMS is enabled, radeon module freezes system on load

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=28592

           Summary: When KMS is enabled, radeon module freezes system on
                    load
           Product: xorg
           Version: unspecified
          Platform: All
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: reilithion at gmail.com
         QAContact: xorg-team at lists.x.org


On some systems, when kernel mode-setting is enabled, attempting to load the
radeon module at any time will cause the system to freeze and become
non-responsive.  If the radeon module is compiled into the kernel, the system
will freeze during boot.

This bug was introduced in commit 6a9ee8a to the Linux kernel (affecting users
of any kernel later than version 2.6.33).

Commenting out the following lines in drivers/gpu/drm/radeon/radeon_bios.c will
work around the issue:

if (r == false)
    r = igp_read_bios_from_vram(rdev);

According to Dave Airlie:
Its trying to read the BIOS from VRAM, but the GPU probably isn't posted yet,
so the VRAM isn't setup.  We used to check for that only on IGP chips, but I've
see the BIOS in VRAM on the switcheroo machines as well so I dropped the check
for IGPs but broke unposted GPUs

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