Comment 0 for bug 356381

Created an attachment (id=19535)
Dmesg snippet with added backtrace

Starting X on a kernel with CONFIG_HIGHMEM64G leads to panics, oopses and bugs with backtraces pointing to different unrelated places. This does not happen with either CONFIG_NOHIGHMEM or CONFIG_HIGHMEM4G.

I put a breakpoint on drmIoctl and found that drmIoctl(fd=16, request=25689, arg=0x0) leads to the above mentioned behaviour. Full backtrace:
#0 drmIoctl (fd=16, request=25689, arg=0x0) at xf86drm.c:183
#1 0xb7abf4da in drmCommandNone (fd=16, drmCommandIndex=25) at xf86drm.c:2285
#2 0xb79ecf70 in I830EnterVT (scrnIndex=0, flags=0) at i830_driver.c:3644
#3 0xb79f1e68 in I830ScreenInit (scrnIndex=0, pScreen=0x8219638, argc=1,
    argv=0xbfd17d04) at i830_driver.c:3412
#4 0x08070cfc in AddScreen (pfnInit=0xb79f0970 <I830ScreenInit>, argc=1,
    argv=0xbfd17d04) at main.c:690
#5 0x080ae954 in InitOutput (pScreenInfo=0x81f2360, argc=1, argv=0xbfd17d04)
    at xf86Init.c:1089
#6 0x08071409 in main (argc=1, argv=0xbfd17d04, envp=0xbfd17d0c) at main.c:310

I am using:
drm-intel-next branch of Erics linux2.6:
b34c87315b1a2822111fc8ef744ef504f9be2f85

master of xf86-video-intel (with patch increasing initial allocation of offscreen memory, i have not figured out why i need it, yet):
74571363539426abeb0a1af11f3bb545d91ed6c2

master of xserver(plus setxkbmap workaround):
1feb69eb63e6739ff5db255ad529e84adf941a10

master of drm:
728d8e226f1bc12f50f710cc96bbb2a25f72ada3

This is using exa acceleration and dri, no dri2.

Attached is part of the output of dmesg, with the backtrace added at the correct place. This is actually the result of three runs, in the first run i got the long dmesg snippet, in the second run i found exactly which drmIoctl call leads to panics, and the third run provided the actual backtrace.