Re: booting btrfs

[Chris Murphy]

On Dec 19, 2013, at 11:14 AM, Vladimir 'φ-coder/phcoder' Serbinenko 
<address@hidden> wrote:

> On 19.12.2013 17:13, Andrey Borzenkov wrote:
>> В Mon, 28 Oct 2013 01:44:26 +0100
>> Vladimir 'φ-coder/phcoder' Serbinenko <address@hidden> пишет:
>> 
>>> I changed in trunk to make / refer to real root and modified
>>> grub-mkrelpath to follow the same convention, even if disk is mounted
>>> with subvolid.
>>> 
>> 
>> Can it cause compatibility issues? It means if config file that works
>> for grub before this change will stop working after. So e.g. attempt to
>> "configfile /file/from/partition/with/old/grub-mkconfig" will fail.
>> 
> Normally I'd consider this a problem but the current behaviour is the
> intended one, just back when the code was written thre were no changing
> default yes
>> May be subvolume support should use different syntax. Something like
>> 
>> (hd0,1){sv=subvolume}/xxx
>> (hd0,1){svid=NNN}/yyy
>> 
> This would complicate the code a lot and commit us to maintaining it
> long-term. Given that btrfs isn't clasified as stable, I consider this
> behaviour change acceptable and it's better to handle this now rather
> than perpetuating the issue.

I tend to agree. It'd also be a really small population of possible breakage, 
because it also requires the default subvolume to have been changed for 
breakage to happen.

I'm also going to opine that knowledge of configfile, is about as obscure as 
changing the btrfs default subvolume. I think if someone knows about 
configfile, even though it's orthogonal to btrfs, that they will have some idea 
how to troubleshoot or where to go to get help if boot breaks as a result of 
this change.


Chris Murphy