Re: lvm module can't see USB disks' volume group

[Andrei Borzenkov]

14.02.2017 06:56, Alexandre Oliva пишет:
> On Feb 11, 2017, Andrei Borzenkov <address@hidden> wrote:
> 
>> Could you show exact message?
> 
>> Assuming the actual error was "hd0 cannot get C/H/S values",
> 
> I'm pretty sure that was it.
> 
>> it is output when INT13 AH=08 fails and disk does not support
>> LBA (i.e. INT13 AH=41 or AH=48 failed previously as well).
> 
>> As BIOS is capable of loading core.img itself off this disk, it is
>> obviously capable of working with it. So we need to figure out what BIOS
>> returns and how to work around it. If you can compile GRUB we can try
>> add debug output to see what happens.
> 
> I'll look into plugging debug messages at appropriate spots.
> 
> I don't suppose there's a GRUB module that enables one to issue INT13
> commands interactively, is there? 

There is not but it could fairly easily be added to biosdisk that
contains all those routines.

> That would make it easy to perform
> interactive experimentation.  I suppose I could see whether FreeDOS has
> the 'debug' command I used to use to do this on another OS back in my
> pre-GNU days ;-) Those skills of mine have certainly grown rusty over so
> many years, but looking at the GRUB code, I'm pretty sure I can still
> figure out how to interact with the disks through the BIOS, and figure
> out why GRUB can load core.img but not access disk partitions.
> 
> Thanks for the feedback so far.  Expect to hear back from me in the
> not-too-distant future.
>