Re: Embedding a file into core.img

[Arbiel (gmx)]

In fact, this is a first try. My goal is to look for a partition name, 
and not a UUID. And when the partition has been found, I will boot 
immediately, without any user action. The USB keys are to be "regular" 
NTFS or FAT keys, without any track of Linux

Regarding the list of modules to include, I relied on the Grub Manual 
which reads, in point 5.4

After the embedded configuration file (if any) is executed, GRUB will 
load the ‘normal’ module (see normal), which will then read the real 
configuration file from $prefix/grub.cfg. By this point, the root 
variable will also have been set to the root device name. For example, 
prefix might be set to ‘(hd0,1)/boot/grub’, and root might be set to 
‘hd0,1’. Thus, in most cases, the embedded configuration file only needs 
to set the prefix and root variables, and then drop through to GRUB's 
normal processing. A typical example of this might look like this:

     search.fs_uuid 01234567-89ab-cdef-0123-456789abcdef root
     set prefix=($root)/boot/grub

(The ‘search_fs_uuid’ module must be included in the core image for this 
example to work.)

And this was confirmed by the file /boot/grub/moddep.lst and more 
precisely on the result of the command

cat /boot/grup/moddep.lst | grep search

which reads

search_fs_uuid:
search_fs_file:
search: search_fs_uuid extcmd search_fs_file search_label
search_label:

which makes me understand I only need the search_fs_uuid module (or the 
search_label module to look for a partition by its name).

Where can I find reliable information ?


Le 20/03/2013 18:40, Andrey Borzenkov a écrit :
> В Wed, 20 Mar 2013 10:34:46 +0100
> "Arbiel (gmx)" <address@hidden> пишет:
>
> > Hi
> >
> > I try to record in the MBR of USB keys an autonomous MBR (no support of
> > any other directory or file) to boot a PC with the system located on a
> > partition whose name is predefined "cielos", and in case this fails, to
> > chainload to the hd0's MBR.
> >
> > I've understood from Grub's Manual that to achieve such a goal, I have
> > to embed the file using option -c of grub-mkimage.
> >
> > I have now modified the --grub-mkimage option to point to the shell
> > script which creates /media/maisonnette/grub/core.img and from there I
> > have been able to imbed the file and launch a boot process. However,
> > this process failed, with a "no such device : the uuid I used in my
> > search.fs_uuid command" whereas such a device exists on my external device
>
> You need to include much more of grub modules than you did. At least
> you need disk driver and filesystem driver to read UUID.
>
> grub-install creates exactly the same embedded config. Why do not you
> simply use it?
>
> > The imbedded file reads
> >
> > search.fs_uuid 0aceef09-a694-4105-bade-2dca95a09a08 root
> > set prefix=(root)/boot/grub
> >
> > and a sudo blkid | grep 0aceef09-a694-4105-bade-2dca95a09a08 responds
> >
> > /dev/sdb5: LABEL="cielos" UUID="0aceef09-a694-4105-bade-2dca95a09a08"
> > TYPE="ext4"
> >
> > I try to understand why the search fails.
> >
> > Le 20/03/2013 04:18, Andrey Borzenkov a écrit :
> > > В Wed, 20 Mar 2013 00:15:07 +0100
> > > "Arbiel (gmx)" <address@hidden> пишет:
> > >
> > > > Hi
> > > >
> > > > I'm trying to embed a file into core.img. I followed instructions from
> > > > GNU Grub Manual's 5.4 Embedding a configuration file into Grub and tried
> > > > to replicate the example given there with a config file figuring two lines
> > > >
> > > >         search.fs_uuid the_uuid_of_my_partition root
> > > >         set prefix=($root)/boot/grub
> > > >
> > > >
> > > > I used the following commands
> > > >
> > > > #! /bin/bash
> > > > cd "${1}"
> > > > cat 1> grub/embed.cfg <<EOF
> > > > search.fs_uuid 0aceef09-a694-4105-bade-2dca95a09a08 root
> > > > set prefix=($root)/boot/grub
> > > > EOF
> > > > sudo grub-mkimage -c 'grub/embed.cfg' -o 'grub/grub-image' -O i386-pc -d
> > > > '/usr/lib/grub/i386-pc' -C none search_fs_uuid
> > >
> > > -O and -d together are redundant.
> > >
> > > > sudo chmod +x 'grub/grub-image'
> > > > sudo grub-install --boot-directory=/media/maisonnette
> > > > --grub-mkimage=grub/grub-image /dev/sdb 2>grub/msg.log
> > >
> > > --grub-mkimage points to program to create image, not to image itself.
> > >
> > > You do not explain what you attempt to achieve. May be using grub-rescue
> > > to build ISO image that includes full grub and can optionally include
> > > arbitrary files would be easier?
> > >
> > > > I get the following error message
> > > >
> > > > grub/grub-image: 1: grub/grub-image: Syntax error: word unexpected
> > > > (expecting ")")
> > > >
> > > > Can anybody tell me what's wrong, knowing that my partition
> > > > /media/maisonnette has nothing to do with the
> > > > 0aceef09-a694-4105-bade-2dca95a09a08 partition.
> > > >
> > > > Thank you
> > > >
> > > > I used the following command
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Help-grub mailing list
> > > > address@hidden
> > > > https://lists.gnu.org/mailman/listinfo/help-grub