[LinuxBIOS] MB1030 / 3036 VGA comes up :D

Richard Smith smithbone at gmail.com
Tue May 2 17:49:51 CEST 2006

On 5/2/06, Ronald G Minnich <rminnich at lanl.gov> wrote:
> Richard Smith wrote:
> > Did you disable the SMI interrupt trap for access to VGA registers?
> > That may be getting fired and tripping things up.
> Man, this is a weird one.
> Disabling SMI on this thing can be touchy. Steve?

I think we are ok.  There is no SMM in the whole system.  The GX1
actually has real PCI config space registers.  And since he has an
external VGA VSA isn't necessary to do any of the VGA stuff.  But
Steve's previous mail on _completely_ disabling the internal VGA of
the cs5530 also mentioned that for an external setup some SMM trap
needs to be disabled.

I just went back and re-read steve's mail:

>If the F4 Video Configuration trap bit (F0, Index 42h, bit 1) is set,
the system will generate >SMIs when trying to access the PCI header
registers.  This should be clear for a non-SMM >system.

So he was talking about PCI acceses not generic IO accesses.  Not what
I was thinking.

What I was thinking of was the power mangement traps on the the IO
access.  But I just looked at the datasheet and they default to
disabled.  So unless we are turning them on I don't think they are

>> So its crashing 'inside' of a printk.  0x3cf is a VGA index register.

>Well, I think so. Many logs looks like the one above. The first
>character is printed. Than nothing no more.

Man, this just smells like some sort of interrupt problem.  Can we
have printk do a cli() and  disable all interrupts when it runs?

Richard A. Smith

More information about the coreboot mailing list