Re: getting grub's view of disk geometry from "grub rescue>" prompt?

[Nathan Stratton Treadway]

On Fri, Mar 15, 2019 at 21:54:27 +0100, Pascal Hambourg wrote:
> Sorry, the position and size information is shown only when the
> module "ls" is loaded. I thought that running normal_exit to exit
> normal mode and go back to rescue mode would be the same as booting
> straight into rescue mode, but it is not : loaded modules are still
> loaded.
> 
> So you must either boot with another GRUB in normal mode, or include
> the "ls" module in the core image when installing GRUB with

Okay, that makes sense....  



> You can try dichotomy. Create a partition starting at 50% of the size.
> Mount it and install GRUB using the mount point as boot directory :
> 
> grub-install --boot-directory=<mount-point> /dev/xxx
> 
> If GRUB boots in normal mode, repeat at 75%. If it boots in rescue
> mode, repeat at 25%. And so on.

Unfortunately I don't think that procedure will work reliably, because
grub could boot fine from a bigger-than-the-unknown-threshold partition
if the /boot directory contents happened to be installed early in the
partition... but then later fail to boot against that that same
partition if the files got moved near the end of the filesystem.


                                                        Nathan

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