Re: GPT attributes in dkwedge [PATCH]

[Martin Husemann <martin%duskware.de@localhost>]

On Sat, Sep 16, 2023 at 06:51:40AM -0000, Michael van Elst wrote:
> You can already specify the root in boot.cfg.

OK, the man page needs an update.

> >It would also be cool if boot.cfg could specify the partition to load
> >the kernel from via something similiar to NAME=.
> 
> You can already specify the disk to load the kernel from with NAME=.

This is not documented in boot.cfg either (but it is in boot(8)).

> >don't understand how you get this far at all with multiboot. And I think
> >multiboot can pass a command line, so root=dev support and make it equivalent
> >to the boot.cfg rootdev statement would solve it too.
> 
> The multiboot support code in the kernel already interprets the passed
> command line, including a "root" option, and this also allows to pass
> a wedge name.

Great, so we are nearly there!

> There is one caveat. Since all x86 bootloader data is funneled through
> the bootinfo structure we have:
> 
> struct btinfo_rootdevice {      
>         struct btinfo_common common;
>         char devname[16];       
> };
> 
> So we have 16 chars to store the identifier (including a NAME= or
> wedge: prefix), that's not enough for a UUID.

So we should create btinfo_rootdevice2 and extend that size to
something more reasonable nowadays or with variable length (and have
the bootloader pass the extended structure if strings are longer).

Martin