Bug 36385 – LiveCD high-res console fails on SiS chipset with LCD monitor

• Product: Gentoo Release Media
• Status: RESOLVED TEST-REQUEST

[Description Jamie Saker 2003-12-23 12:08:22 UTC]

Following boot option selection (in low-res), LiveCD proceeds to a high-res console screen (blue background with Gentoo logo). However, when encountering SiS chipset and an LCD monitor, the system cannot find a suitable mode and loses video output (resulting in a LCD message such as "VGA mode not supported" per LCD firmware operation).

SiS is not the nicest of chipsets, but it is increasingly common on Biostar motherboards. This link explains chipset LCD vs. CRT bridge and details supported LCD modes (which LiveCD may not be properly set to handle per SiS presently):

http://www.winischhofer.net/linuxsis630.shtml

Have confirmed this with AMD XP and x86 LiveCDs - both generate same error. Have tested with three different SiS chipset systems and LCD panel - all yield failure.


Reproducible: Always
Steps to Reproduce:
1. Boot a LiveCD in a SiS chipset system with LCD.
2.
3.

Actual Results:  
LCD monitor loses sync and reports that Gentoo LiveCD has gone into an
unsupported mode per LCD's firmware message; e.g. "VGA mode not supported."


Expected Results:  
Detected an appropriate, supported mode and used it. If this is not possible, a
message indicating "LCD video device not supported for your video chipset under
this LiveCD image. Please use a CRT for LiveCD installation" might be suitable
for a workaround.

SiS Linux video mode link:
http://www.winischhofer.net/linuxsis630.shtml

WORKAROUND: Use CRT instead of LCD panel.

[Comment 1 Bob Johnson (RETIRED) 2003-12-23 12:21:06 UTC]

You can boot with "nofb" to disable framebuffer.
Options are on F2 help page (before fb starts) and in the docs