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

[Myles Watson]

On Fri, May 14, 2010 at 1:49 PM, Joe Korty <joe.korty at ccur.com> wrote:
> 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.
I wonder if that could be partly due to the ACPI implementation too.

> 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.
It seems like you have a pretty specific special case.  Maybe we
should create a CONFIG_EXTRA_HEAP that depends on CONFIG_EXPERT that
lets you add heap.

> 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.

Sounds like fun.

Thanks,
Myles