Re: Booting Debian 10 installer ISO from USB

[Brian <ad44@cityscape.co.uk>]

On Sat 23 Nov 2019 at 11:00:58 -0600, prueba@finsakxim.com.mx wrote:

> El 2019-11-22 16:41, Brian escribió:
> > Try this for the kernel boot options:
> > 
> >  "iso-scan/filename=$iso_path priority=low"
> > 
> > In other words, replace two of the options with iso-scan/filename=. It
> > works for me when the ISO, vmlinuz and initrd.gz are all in /boot.
> 
> This
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=841135
> would explain why it works for you, as well as in other cases.
> 
> It seems to only work at maximum level 1 directories; further, as in my
> case, no longer works.
> Pity...

Thank you for the link. I had not seen this report before. One bit of it
is the statement:

 > From what I understand now, iso-scan is not meant to use
 > any iso filename supplied to it via grub command line, but
 > it rather prefers to scan the USB stick for usable images
 > itself, and then present the user with a menu.

My understanding is that iso-scan/filename= simply says which ISO is to
be searched for. But, additionally, iso-scan needs to be told where to
search by being informed of the device or partition to use or by getting
it to look at every device/partition on the system or by extra kernel
command line options.

I put two Debian ISOs in /boot/iso and had a similar grub.cfg to yours:

  iso_path=/boot/iso/debian-10.2.0-amd64-xfce-CD-1.iso
  export iso_path
  search --set=root --file "$iso_path"
  loopback loop "$iso_path"
  menuentry "Test" {
     linux /boot/vmlinuz  iso-scan/filename=$iso_path priority=low
     initrd /boot/initrd.gz
  }

I get a list of sixteen partitions and devices and choose the one that I
know holds the ISOs (/dev/sdg1). This comes up with (as it did for you):

 > The quick scan for installer ISO images, which looks only
 > in common places....

But a full disk search immediately scans /dev/sdg1 and presents a choice
between the two ISOs.

If our experience differs, I cannot explain why.

-- 
Brian.