[coreboot] [PATCH] Promote heap sizing to first-class Kconfig citizenship.

Joe Korty joe.korty at ccur.com
Fri May 14 21:49:28 CEST 2010

On Fri, May 14, 2010 at 03:19:45PM -0400, Myles Watson wrote:
> On Fri, May 14, 2010 at 1:11 PM, Joe Korty <joe.korty at ccur.com> wrote:
> > Promote heap sizing to first-class Kconfig citizenship.
> >
> > Changing the heap size is something that those, like me,
> > with large PCI device trees need to do. ?Therefore heap
> > size should appear as a normal, user-answerable question
> > within the Kconfig build system.
> I think the difference here is that you're a developer (not a user)
> once you start touching the code.  Users shouldn't have to worry about
> the heap size.  It should be set larger in your mainboard Kconfig if
> the mainboard needs more heap space.

Some background:
The reason I'm looking at coreboot is that standard BIOSes
(apparently) run out of memory while doing the bus walk,
when I plug a PCI-e expansion chassis into the motherboard
and populate it.  The BIOS will either lock up or the OS
will boot but what the OS sees for a PCI Bus (via lspci
-tv) is clearly corrupt.

So my job was/is to do an experiment to see if our problems
are indeed due to out-of-memory issues in standard BIOSes, and
if so, if coreboot could be a useful way around this issue.

And indeed, the first time I booted coreboot with a
populated PCI-e chassis attached, I got an out-of-memory
halt from coreboot.  Increasing CONFIG_HEAP_SIZE to
0x10000 (ie, 4x) got the system to boot, and lspci -tv
looks good also.  I have yet to try intermediate values.

Unfortunately we have an even bigger PCI-e loaded expansion
chassis (configuration #2), for which coreboot also hangs.
It's not an out-of-memory hang; it happens (apparently)
during the bus walk.  I haven't looked into this hang in
detail yet, so I don't have much to report.  But I do fear
it may be something more fundamental.


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