Re: 'device ...' line in grub.cfg

[Andrei Borzenkov]

On Thu, Jun 2, 2016 at 4:53 PM, David Kaspar [Dee'Kej]
<address@hidden> wrote:
> Hello Andrei,
>
> I honestly don't know what generated that line, but I have a hunch it just a
> debugging code output. If you look at 'grub-core/kern/efi/efi.c' (in current
> grub2 repository), at line 763, you will see this:
>
>> grub_printf ("/HD(%u,%llx,%llx,%02x%02x%02x%02x%02x%02x%02x%02x,%x,%x)",
>>          hd->partition_number,
>>          (unsigned long long) hd->partition_start,
>>          (unsigned long long) hd->partition_size,
>>          (unsigned) hd->partition_signature[0],
>>          (unsigned) hd->partition_signature[1],
>>          (unsigned) hd->partition_signature[2],
>>          (unsigned) hd->partition_signature[3],
>>          (unsigned) hd->partition_signature[4],
>>          (unsigned) hd->partition_signature[5],
>>          (unsigned) hd->partition_signature[6],
>>          (unsigned) hd->partition_signature[7],
>>          (unsigned) hd->partmap_type,
>>          (unsigned) hd->signature_type);
>
> So, this is part of grub2 (U)EFI, even though it was backported to
> grub-legacy.
>

grub2 neither writes into grub.cfg (wuth single exception of
grub-mkconfig script) nor does it even have "device" directive. So if
your question is what HD(...) means - this is EFI Media Device Path;
you can find detailed description in EFI specification on
http://www.uefi.org/. Other formats refer to other device paths.

Could you clarify your question? Do you want to know what individual
fields mean or how grub legacy is using these specification?

> Best regards,
>
>
> David Kaspar [Dee'Kej]
> Associate Software Engineer
> Brno, Czech Republic
>
> RED HAT | TRIED. TESTED. TRUSTED.
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>
> On Thu, Jun 2, 2016 at 3:48 PM, Andrei Borzenkov <address@hidden>
> wrote:
>>
>> On Thu, Jun 2, 2016 at 4:01 PM, Clayton Spicer <address@hidden> wrote:
>> > Hello everyone,
>> > I'm looking into a high priority issue we have and trying to find out
>> > what the 'device ....' line does in grub.cfg.
>> >
>> > For example:
>> > device (hd0) HD(1,123,123abc,01234567-89abcdef-01234567-89abcdef)
>> >
>>
>> This looks like grub legacy patched to support EFI (unless this line
>> is there by mistake). Upstream grub legacy never supported EFI as far
>> as I know, so unless someone is familiar with it, your best bet is to
>> contact patch author.
>>
>> If I am wrong, please tell grub version (but this line is unlikely
>> from grub2 grub.cfg either).
>>
>> > In addition to HD, there also seems to be CD, Vendor, File,
>> > UnknownMedia, UnknownBIOS, which each take different parameters. I'm
>> > trying to find out exactly what this line actually does, what
>> > parameters it takes, and so on - any information anyone might have
>> > would be much appreciated.
>> >
>> > Thanks!
>> > Clayton
>> >
>> > _______________________________________________
>> > Help-grub mailing list
>> > address@hidden
>> > https://lists.gnu.org/mailman/listinfo/help-grub
>
>