[coreboot] How to make graphical issue go away with 4GB of ram

Denis 'GNUtoo' Carikli GNUtoo at no-log.org
Sat Jun 30 23:47:13 CEST 2012

On Sat, 2012-06-30 at 12:44 -0600, Marc Jones wrote:
> On Sat, Jun 30, 2012 at 12:01 PM, Kyösti Mälkki <kyosti.malkki at gmail.com> wrote:
> > On Sat, 2012-06-30 at 18:18 +0200, Denis 'GNUtoo' Carikli wrote:
> >> Hi,
> >>
> >> me and Kyösti Mälkki(kmalkki on IRC) figured out how to workarround the
> >> following problem:
> >> If I installed 4GB of ram in the m4a785t-m the screen comes up,however
> >> it's black.
> >> If I only installed 2GB of ram it worked fine.
> >>
> >> I made a patch(I'll send it right after that email) but it seem to break
> >> graphics for the case where 2GB of ram is installed.
> >>
> >> So I wonder what would be the correct fix(a fix that would work for
> >> every cases).
> >>
> >> Explanation of the patch that will be sent right after the mail:
> >> "basek - mmio_basek;" should be 1048576 (1G):
> >> According to Kyösti Mälkki the correct value for the sizek is 1048576.
> >> So I looked for what could create that size and found that.
> >> I'm not convinced that "basek - mmio_basek" is the right fix but at
> >> least we're in the right direction.
> >
> > My explanation of the issue: uma_memory_size must reduce the size of the
> > last RAM resource _below_ 4GB. It now touches the last RAM resource,
> > even if located over 4GB.
> Yes, The UMA graphics memory is allocated in the lower 4GB. I think
> that should be happening in mainboard.c. See the AMD reference
> platforms.
Do you mean the following:

uint64_t uma_memory_base, uma_memory_size;

int add_mainboard_resources(struct lb_memory *mem)
        lb_add_memory_range(mem, LB_MEM_RESERVED,
                uma_memory_base, uma_memory_size);
        return 0;

With the addition of "select HAVE_MAINBOARD_RESOURCES" in Kconfig ?

if so I already tried that change alone(without other changes) and it
didn't work, I don't remember what it did exactly tough, I can retry if


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