[coreboot] Skylake FSP 1.1 without verstage?

[Aaron Durbin]

On Wed, Oct 5, 2016 at 6:25 PM, Trammell Hudson <hudson at trmm.net> wrote:
> On Wed, Oct 05, 2016 at 03:19:11PM -0500, Aaron Durbin wrote:
>> On Wed, Oct 5, 2016 at 3:08 PM, Trammell Hudson <hudson at trmm.net> wrote:
>> > CBFS: 'Master Header Locator' located CBFS at [a00100:ffffc0)
>> > CBFS: Locating 'fallback/ramstage'
>> > CBFS: Found @ offset afc0 size 12e29
>> > Decompressing stage fallback/ramstage @ 0x7abbffc0 (743408 bytes)
>> > Loading module at 7abc0000/7abc0000 with entry 7abc0000. filesize: 0x28d88 memsize: 0xb57b0
>> > Processing 2472 relocs. Offset value of 0x7aac0000
>> > src/arch/x86/boot.c:223: jumping to 7abc0000
>> >
>> > (and then it crashes)
>>
>> You can try writing characters to the serial console in
>> src/arch/x86/c_start.S. Do you have the ability to read post codes?
>> That's the best way to know how deep you are getting through c_start.S
>> in the jump to ramstage.
>
> Thanks to a servo board, I can read the port 80 codes and verified
> that the instruction causing the problem is the lgdt / jmp combo
> in c_start.S:
>
> _start:
>         cli
>         lgdt    %cs:gdtaddr
> #ifndef __x86_64__
>         ljmp    $0x10, $1f
> #endif
> 1:      movl    $0x18, %eax   // <---- never reached with relocatable
>
>

I don't understand that behavior at all. When you objdump -d -r -S
ramstage.debug do you see the ljmp instruction?

You can dump the ramstage relocations (with is still enabled) by changing

#define PK_ADJ_LEVEL BIOS_DEBUG

in src/lib/rmdoule.c.


>> [...]
>> I'm not sure why it's crashing (or just not spitting anything out).
>> You could certainly try disabling RELOCATABLE_RAMSTAE and see if that
>> fairs better.
>
> It looks like CONFIG_SOC_INTEL_SKYLAKE forces relocatable ramstage;
> I've modified src/soc/intel/skylake/Kconfig to disable it and now
> it makes it all the way into the payload.
>
> And by adding the i915 driver to the Linux payload, it is able to
> bring up the console in a miniscule font!
>
> https://www.flickr.com/photos/osr/30026718432/in/photostream/lightbox/
>
> I'm declaring today a huge success!
>
> --
> Trammell
>