Re: Re: Grub2 on UEFI

[Michal Suchanek]

On 29 January 2010 19:45,  <address@hidden> wrote:

>
>>
>>  >
>>  >
>>  >
>>  > ?????????????????? If it possible to exit grub with EFI ERROR to process 
>> loading the
>>  > next loader?
>>  >
>>
>>
>>  > Exiting grub is in itself an error, an OS loader should never end.
>>  > So look for some quit command.
>>
>>
>> Why? I think it was in old BIOS times. EFI was a boot order concept, in one 
>> loader is failed, another
>> one is trying to boot.
>>
>> If the boot loader exited it has obviously not loaded any OS hence it
>> has failed.
>
> Here I disagree. In old BIOS times we got only one try to load OS - the MBR 
> got the jump to the loader (lilo, grub, ntldr, whatever), and if the loader 
> fail - the whole booting it failed (however loader can "pass" execution to 
> another loader)
>
> Now, EFI has the concept or order  of loaders. The EFI firmware loader has a 
> list of loaders, if the first one (say grub) is failed, it will try next one 
> (say Windows Boot Manager). So, Windows Boot Manager is executed by EFI 
> Firmware loader, not by the grub>

Yes, you said it yourself - if it has failed. So any time the loader
exits it is a failure.

>>
>>
>> ·         What about  device names in grub2 for EFI? The problem  is that
>> old device names were based on BIOS device names, and it seems that in EFI
>> it's not the same. For example, what disk is hd0?
>>
>> Unfortunately, the disk order is firmware specific and nothing can be
>> done about that. You should look at disk content or use UUIDs.
>
> Please, I need more info on it =)
> How can I identify the disk using disk content or UUID.
>
> For example, I got my kernel on NTFS partition and now smth like
>
> (hd2,1)/Loader/Kernel/vmlinux
>
> is written in grub config. Imagine that new disk is inserted oor new 
> partition is created, the booting will fail. For example I need to examine 
> all partitions and if one has a dir structure /Loader/Kernel/vmlinux and/or 
> UUID ... - load the kernel. How can I do that? I can't find mych information 
> on the topic

You probably want the search command.

The Debian scripts produce something like this:

search --no-floppy --fs-uuid --set <some long string of
numbers,letters and dashes here>

In GNU/Linux (with modern udev) you get can see the UUID mapping in
/dev/disk/by-uuid.

Disk check tools also typically report it.

If you use MS tools it might be named and formatted slightly
differently, though.

Thanks

Michal