[issue769] Please add a caveat regarding findiso boot option

[Christoph Biedl]

New submission from Christoph Biedl <grml.fksi at manchmal.in-ulm.de>:

Severity: minor

Hi,

booting grml from hard disk using findiso= failed mysteriously on some
computers: The initrd could not locate the ISO image and therefore
dropped me into the (very) restricted shell.  The same configuration
and file layout worked like a charme on other computers.

With the help of #grml I found the reason as follows:
* The file system of that partition (here: /dev/sda1) is ext[23].
* The very first sector contains a boot sector, installed by
  (perhaps some old version of) grub.

Then, "/lib/udev/vol_id /dev/sda1" returns, at least sometimes
(...)
ID_FS_TYPE=vfat
(...)
or fails to identify the device at all.

Assuming grml's initrd does the same, this explains the error.

Solution: Clear out that sector, e.g. doing
| dd if=/dev/zero bs=512 count=1 of=/dev/sda1
and make sure your boot loader is still intact, in case of doubt:
Re-install it, preferrably on /dev/sda.

Could you please drop an according caveat in the documentation? That
would have saved a lot of frustration for me.

Suggestion:

Caveat (regarding the findiso boot option): 
Under certain circumstances grml fails to identify the partition for
the grml .iso file, thus fails to boot after the "Searching for GRML
file" message. This may happen if the filesystem where the .iso file
is stored, is ext2 or ext3. If you're sure all file names are correct
etc., please check whether "/lib/udev/vol_id <device>" actually
returns that filesystem.

Regards,
    Christoph

----------
messages: 2684
nosy: grml.fksi
status: unread
title: Please add a caveat regarding findiso boot option

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