Re: Possibly erroneous "device not present" message during boot

[Richard Owlett <rowlett@cloud85.net>]

On 04/13/2017 10:48 AM, Pascal Hambourg wrote:
> Le 13/04/2017 à 13:40, Richard Owlett a écrit :
> > On 04/12/2017 02:03 PM, Pascal Hambourg wrote:
> > > Le 12/04/2017 à 20:33, Richard Owlett a écrit :
> > > > On 04/12/2017 12:13 PM, Pascal Hambourg wrote:
> >
> > [snip]
> > > > > - while the SD card is inserted, in the GRUB menu press "c" to enter a
> > > > > GRUB shell and report the result of the "ls" command.
> > > >
> > > > (hd0) (hd0, msdos9) (hd0, msdos8) (hd0, msdos7) (hd0, msdos6)
> > > > (hd0, msdos5) (hd0, msdos1) (hd1) (hd1, msdos1)
> > >
> > > Some BIOS expose a removable media only when booting from it, so my
> > > theory was that your BIOS did not expose the SD card and GRUB could
> > > not see it. The result of ls proves me wrong.
> > >
> > > Can you also report the output of "ls (hd1,msdos1)" to check what GRUB
> > > sees of the partition on the card ?
> >
> > It gives the partitioning description, UUID, and label of the USB flash
> > drive that was plugged in. It is FAT formatted and used to exchange
> > information with my Windows machine.
>
> USB drive ? Then (hd1) is not the SD card ? If you boot with no USB
> drive plugged in, there is no (hd1), right ?

Correct on all counts. IIUC the SD card slot is connected to a USB hub. 
When not the booted system, it automatically mounted in the same 
apparent manner as a USB flash drive.

> Then the SD card does not
> appear as a usable device for GRUB and my twisted theory may still be
> correct after all.
>
> > > > Any suggested reading on the "BASH like shell" I just used?
> > >
> > > The GRUB manual at <https://www.gnu.org/software/grub/manual/grub.html>
> >
> > It was what prompted me to ask ;/
>
> Sorry, I do not know any better documentation.