Re: Bug#584846: Detects only 64MB and fails to boot on Intel Green City board if e820 hooked by GRUB2

H. Peter Anvin
2010-06-13T00:16:46Z

On 06/12/2010 05:07 PM, Josh Triplett wrote:
> On Sat, Jun 12, 2010 at 04:02:44PM -0700, H. Peter Anvin wrote:
>> On 06/12/2010 03:26 PM, Josh Triplett wrote:
>>>
>>> Everything looks identical except for the region GRUB hooked right below
>>> the first reserved region; the unhooked version has available memory
>>> from 0-0x9cbf0, and the hooked version has available memory from
>>> 0-0x9cba0, then reserved from 0x9cba0-0x9cbec, then 4 bytes of available
>>> memory, and then the same reserved region as before.
>>
>> Actually... are both these done by chainloading Grub (with and without
>> mapping), or is the unhooked done without chainloading Grub at all?
>>
>> To me it looks like something is chaining INT 15h even in the
>> "unchained" case...
>
> The "unhooked" case still chainloaded from GRUB, just without calling
> drivemap and thus without hooking anything. I can test without
> chainloading from GRUB, though to the best of my knowledge GRUB doesn't
> hook int 15 unless it needs to intercept e820 (and e801 and 88).
>
> - Josh Triplett

Well *something* is... and it might not be Grub but one of the expansion
ROMs. If so, the problem is probably Grub stepping on the expansion ROM
by not honoring FBM.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.