Re: Dualbooting with guixsd not handling grub installation

[Martin Castillo]

Hi

On 11.12.2017 10:39, Ludovic Courtès wrote:
> Hello,
> 
> Mathieu Othacehe <address@hidden> skribis:
> 
>>>> This could be done by adding a cli argument for reconfigure or allowing
>>>> an empty string in (grub-configuration (target "")).
>>>>
>>>> WDYT?
>>>>
>>
>> An already available option would be to override the grub-installer like
>> this :
>>
>> (define no-op-installer
>>   #~(lambda (bootloader device mount)
>>       (display "no op")))
>>
>> (bootloader (bootloader
>>              (inherit grub-bootloader)
>>              (installer no-op-installer))
> 
> We could even define and document it as ‘no-bootloader’ or something
> like that.
> 
>> I admit this is not ideal, so I would propose two options :
>>
>> * Allow for target field to be #f and do not call the installer when
>> this happends.
> 
> Sounds reasonable.

+1

> 
>> * Precise the --no-bootloader parameter of guix system to deal with
>> multiple cases, for example :
>>
>> --bootloader=[default|no-config-file|no-install|...]
>>
>> WDYT ?
> 
> What would it do in the ‘no-config-file’ case?  Run ‘grub-install’ (or
> similar) without regenerating ‘grub.cfg’?  Does that make sense?

I realised a third option for dualbooting:
menuentry "GuixSD - grub core.img loader" {
  search --set root --label guix-root --hint hd0,gpt3
  multiboot /boot/grub/i386-pc/core.img
}

This loads the guixsd grub image from the filesystem instead of relying
on blocklists. If someone uses different bootloader for the main system
and for guixsd, where the later is multiboot compatible, this would be a
good way to do it. no-install should not forget to create core.img and
other files besides grub.cfg.
I think useful is 'default' (install new bootconfig or, if target is #f,
create it only), 'no-install' (like default with target == #f) and 'no'
(do nothing related to booting).

Martin

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