SISUSB VGA adapter fails to initialize on 1.75

[greenfeld]

1. Attach an SISUSB-using USB VGA adapter to an XO-1.75, and fully reboot said XO (to force the SISUSB xorg.conf file to be used).
2. The X server will die during initialization with a segmentation fault.

Seen with 11.3.1 os27.

[   760.294] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 263, real 262
[   760.368] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 263, real 262
[   760.458] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 267, real 266
[   760.536] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 267, real 266
[   760.612] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 267, real 266
[   760.686] (EE) dovefb(0): mrvlFencePoolStall:sync marker timeout, wait 267, real 266
[   760.702] 
Backtrace:
[   760.703] 0: X (xorg_backtrace+0x2c) [0xa2f94]
[   760.704] 1: X (0x8000+0x5afec) [0x62fec]
[   760.704] 2: /lib/libc.so.6 (__default_rt_sa_restorer_v2+0x0) [0x40368820]
[   760.704] 3: /lib/libc.so.6 (0x4033c000+0x6e128) [0x403aa128]
[   760.704] 4: /lib/libc.so.6 (__libc_malloc+0x7c) [0x403acdc0]
[   760.704] 5: /lib/libc.so.6 (0x4033c000+0x65a74) [0x403a1a74]
[   760.704] 6: /lib/libc.so.6 (0x4033c000+0x6d564) [0x403a9564]
[   760.704] 7: X (RegionValidate+0xcbc) [0x49048]
[   760.705] 8: X (RegionFromRects+0x22c) [0x49a98]
[   760.705] 9: /usr/lib/xorg/modules/libexa.so (0x40635000+0xae94) [0x4063fe94]
[   760.705] 10: X (0x8000+0xd2efc) [0xdaefc]
[   760.705] 11: X (0x8000+0x166800) [0x16e800]
[   760.705] 12: X (miCompositeRects+0x78) [0x16e8e0]
[   760.705] 13: X (CompositeRects+0x7c) [0xcf6f0]
[   760.705] 14: X (0x8000+0xcb8f4) [0xd38f4]
[   760.706] 15: X (0x8000+0xc7c98) [0xcfc98]
[   760.706] 16: X (0x8000+0x26cd0) [0x2ecd0]
[   760.706] 17: X (0x8000+0x1b558) [0x23558]
[   760.706] 18: /lib/libc.so.6 (__libc_start_main+0x118) [0x403516fc]
[   760.706] Segmentation fault at address 0x7
[   760.706] 
Fatal server error:
[   760.706] Caught signal 11 (Segmentation fault). Server aborting

[greenfeld]

Full Xorg log

[greenfeld]

A different stack trace during initialization which leads to a segfault was seen in 11.3.1 os885 for XO-1.75.

We may not fix for this 11.3.1; so it needs to be added to the release notes.

[dsd]

This was also broken in 12.1.0, but has started working in 13.1.0, tested on build 7. :)