[coreboot] Porting to Asus M4A78-EM

Juhana Helovuo juhe at iki.fi
Thu Dec 2 16:53:02 CET 2010

2.12.2010 17:31, Scott Duplichan kirjoitti:

> ]Also a modified Memtest86 can be executed from SeaBIOS, but clearly it
> ]gets a wrong idea of memory regions to test and quickly overwrites the
> ]VGA buffer (display trashed) and its own executable (crash with register
> ]dump). If the memtest is quickly interrupted to configuration menu and
> ]the test region is limited to only, e.g. addresses 300M - 1G, then it
> ]seems to run ok. Memtest claims that it is reading the coreboot tables
> ]to find out RAM areas to test.
> I am not too familiar with memtest86, but an overwrite of the UMA memory
> should be easy to debug. From your e820 map, it looks like the DRAM
> reserved for UMA use is at 30000000-3fffffff. The frame buffer maps the
> same DRAM to a different address, such as D0000000. If the display is
> written, then one of these two ranges is getting written. What is your
> frame buffer address?
> An experiment you could do is add a PCI video card and build without UMA
> graphics support.

Hello Scott,

Coreboot maps the frame buffer (or overall GPU memory) to

Testing without UMA also crossed my mind, but it has to wait until I 
manage to get a VGA card with DVI and PCI or PCI-E, so I can connect to 
the mainboard and monitor. My current junk^H^H^H^Hspare parts box has 
only cards with either analog VGA & PCI or DVI & AGP.

Still, my main concern is not memtest86, but getting Linux to boot at 
least so far that I can see some kernel boot messages to know what is 

Best regards,
Juhana Helovuo

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