Re: Idea: Improve ext2 to allow for embedding

[Pascal Hambourg]

On 13/03/2024 at 11:25, Mate Kukri wrote:
> Do you have a proposed use-case for this in mind?
> On MBR disks there is usually enough space for core.img before the
> first partition.
> On GPT you can simply create a so-called "BIOS boot partition" to
> store core.img.

A use case could be when you do not want to install the GRUB boot image 
in the disk MBR as the primary boot loader but in a partition boot 
sector as a secondary boot loader.

> On Wed, Mar 13, 2024 at 10:22 AM Dr. Tilmann Bubeck <tilmann@bubecks.de> wrote:
> > I would like to propose a change to GRUB to allow embedding (fs_embed)
> > of core.img for ext2/3/4 into the
> > filesystem. This allows the installation of GRUB into ext2 without the
> > need to use (unsafe) block lists.
> >
> > It will be realized using the ioctl(EXT4_IOC_SWAP_BOOT) introduced into
> > Linux 3.10 in 2013. This ioctl basically swaps the data blocks of the
> > associated file with the EXT2_BOOT_LOADER_INO inode. After using the
> > ioctl the code of core.img is stored in the BOOT_LOADER incode of the
> > filesystem and it is not accessible to file system tools anymore. This
> > ensures, that the boot code is safe and installation into a partition is
> > possible.
> >
> > What would you think about this proposal. Are you willing to integrate
> > this, if I develop this for GRUB?
> >
> > Changes will be done mainly in setup.c and ext2.c