Re: Set a bootdrive environment variable.

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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What's the problem with extracting this from $prefix ? This seems to be
a better match if what you want is location of GRUB.
On 31.05.2015 08:42, Andrei Borzenkov wrote:
> В Wed, 27 May 2015 08:55:09 -0400
> Mathieu Trudel-Lapierre <mathieu.tl@gmail.com> пишет:
> 
>> On Wed, May 27, 2015 at 12:04 AM, Andrei Borzenkov <arvidjaar@gmail.com>
>> wrote:
>>
>>> В Tue, 26 May 2015 12:46:07 -0400
>>> Mathieu Trudel-Lapierre <mathieu.tl@gmail.com> пишет:
>>>
>>>> I've been playing with fixing Ubuntu bug 1097570; trying to debug a
>>> script we
>>>> use for the EFI images which detects where to boot from based on the
>>> location
>>>> of a .disk/info file.
>>>>
>>>> Turns out this mostly works, except for the fact that grub appears to
>>> always
>>>> list devices in a specific order, which interferes with the detection if
>>> more
>>>> than one device contains that file.
>>>>
>>>> I think I can make this work appropriately provided we:
>>>>   - Use hints for search --file;
>>>>   - Have some value to pass to --hint= designating the boot drive.
>>>>
>>>
>>> If you always want to use the same device GRUB was booted from why do
>>> you need to search for anything at all?
>>>
>>
>> My understanding from why the search was used is that $root may not have
>> been set for all types of devices (i.e. CDs), and the same built grub
>> images (for EFI) were used on bootable USB and CDs since they are both
>> built from a single ISO.
>>
> 
> That depends on your image. If image defines prefix and drive and/or
> partition is missing (e.g. (,msdos1)) missing parts are derived from
> whatever firmware provides (effectively what ends up in $cmdpath) and
> should be set for any boot media.
> 
> Although I just hit a system (Fujitsu Lifebook S761) which passes bogus
> device path to image that does not match any existing handle, so both
> $cmdpath and $root are not set.
> 
>> In retrospect, having a properly set $cmdpath (or $grub_bootdev or
>> whatever), probably makes this unnecessary.
>>
>>
>>>> Included is a patch that adds a "bootdrive" variable alongside cmdpath;
>>> which
>>>> contains just the drive designation for the boot device, to be used as
>>> such:
>>>>
>>>> search --set=root --hint=$bootdrive --file .disk/info
>>>>
>>>> I'd much appreciate review on that patch :)
>>>>
>>>
>>> You can extract it from $cmdpath using regexp already. In retrospect
>>> having separate variables for device and path would be more flexible;
>>> but $drive is not appropriate name as it can refer to network as well.
>>> Something like $grub_bootdev and $grub_bootpath.
>>>
>>
>> That was one of the reasons I wanted review on it, so thanks!
>>
>> I'm happy to change it to $grub_bootdev or whatever else if we feel having
>> separate variable for this in indeed a good idea (and I'll add what's
>> needed to get $grub_bootpath).
>>
> 
> The problem is that $cmdpath had been around for long enough. If
> $cmdpath is used only after loading normal (that are cases I'm aware
> of) we can make it compatibility variable set by normal without causing
> more core bloat.
> 
>>
>> Mathieu Trudel-Lapierre <mathieu.tl@gmail.com>
>> Freenode: cyphermox, Jabber: mathieu.tl@gmail.com
>> 4096R/EE018C93 1967 8F7D 03A1 8F38 732E  FF82 C126 33E1 EE01 8C93
> 
> 
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