Re: grub-mkimage

[Glenn Washburn]

On Tue, 1 Mar 2022 09:29:52 +0100
Pascal <patatetom@gmail.com> wrote:

> hi (and sorry for this long time),
> 
> thank you for the explanations about the graft point syntax which should
> probably be present in the grub-mkstandalone documentation.
> so, you should replace SOURCE by GRAFTPOINT in the general presentation
> (usage line).

Well, SOURCE can be graphpoint, but it doesn't have to be, which is why
it is the way it is, I'm guessing.

> I was mentioning prefix because three small dots are present after the
> SOURCE argument in the usage line and I thought it was possible to provide
> other arguments and therefore perhaps prefix.

The three dots usually indicate more of what preceded the dots. In this
case, more SOURCE arguments.

> thank you for the proposal but unfortunately I don't think I have the
> knowledge to send patches, even for documentation.
>
> the verbose mode (thanks again),
> 1) the verbose mode is only activated when the set debug=all line is played
> : is it possible to activate it as soon as grub is loaded/launched (at UEFI
> level may be) ?

Not without patching GRUB. The best you can do is set debug=all in the
rescue shell config. It might be nice to have a --debug-all configure
option to turn on debug=all as soon as possible.

> 2) a lot of messages are displayed on the screen and the menu ends up
> taking over : is it possible to capture these messages (with redirection to
> a file may be) ?

Looks like you got what you wanted from QEMU (using serial output, I
presume). GRUB does not enable writing for the most part,
but there is no redirection to a file unfortunately.

Glenn

> regards, lacsaP.
> 
> Le jeu. 10 févr. 2022 à 04:34, Glenn Washburn <development@efficientek.com>
> a écrit :
> 
> > On Wed, 26 Jan 2022 10:34:28 +0100
> > Pascal <patatetom@gmail.com> wrote:
> >
> > > hi,
> > >
> > > thank you Andrei for taking the time to read and answer me.
> > >
> > > I try to reduce the space taken by GRUB as much as possible.
> > > this way, I only have the bootloader and a basic configuration file :
> > >
> > > # ll -h /run/live/bootmnt/efi/boot/bootx64.efi
> > > -rwxr-xr-x 1 root root 584K 26 janv. 07:46
> > > /run/live/bootmnt/efi/boot/bootx64.efi
> > >
> > > # cat /run/live/bootmnt/efi/menu.cfg
> > > menuentry MyLiveSystem {
> > > linux /boot/kernel ...
> > > initrd /boot/initramfs
> > > }
> > >
> > > I tried to remove efi_gop and efi_uga but I always get (at least with
> > Qemu)
> > > the following error message :
> > >
> > > error: no suitable video mode found.
> > > Booting in blind mode
> > >
> > > adding video and/or video_fb modules (which are required/used by efi_*
> > > modules) does not change anything.
> > >
> > > I tried to use grub-mkstandalone but I fail to generate a bootloader that
> > > works as simply as my tiny one.
> > > here is the command used :
> > >
> > > grub-mkstandalone \
> > >    --disable-shim-lock \
> > >    --fonts="" --locales="" --themes="" \
> > >    --modules="linux normal minicmd gzio efi_uga efi_gop fat part_gpt
> > chain"
> > > \
> > >    -o /run/live/bootmnt/efi/boot/test.efi \
> > >    -O x86_64-efi \
> > >    "boot/grub/grub.cfg=/run/live/bootmnt/efi/menu.cfg"
> > >
> > > as root and prefix use (memdisk), I get the following error message :
> > >
> > > error: file `/boot/kernel' not found.
> > >
> > > only the cmdpath variable refers to my disk with (hd0,gpt2)/efi/boot.
> > > it works once the root variable is manually set to (hd0,gpt2) (but not
> > with
> > > (,gpt2)).
> > >
> > > as you are involved in the development of GRUB, I have a small remark
> > about
> > > grub-mkstandalone : the SOURCE parameter is not discussed in its man page
> > > apart from the general presentation (eg. invocation).
> > > I found my last parameter ("boot/grub/grub.cfg=...") on the internet :
> > what
> > > more information/option can be passed ? prefix may be ?
> >
> > If you run "grub-mkstandalone --help", you'll see a line at the bottom
> > saying "Graft point syntax (E.g. /boot/grub/grub.cfg=./grub.cfg) is
> > accepted". This could proabably be worded better and perhaps more
> > detailed. However, "graft-point" syntax is FROM=TO where FROM is a path
> > valid in the host (the one running grub-mkstandalone) and TO is what
> > the files path should be in the memdisk. If the source argument has no
> > equal sign, then it treated as SOURCE=SOURCE. As fas as I can tell
> > that's all that SOURCE is, a list of such arguments.
> >
> > What kind of prefix are you looking for?
> >
> > It would be great if you had any ideas on how to make the documentation
> > more clear or better in some way. If you have some explicit feedback,
> > please let me/us know. And even better, documentation patches welcome!
> >
> > >
> > > a last question (for today ;-)) to which I did not find an answer : is it
> > > possible to switch the bootloader to verbose mode ?
> >
> > If you set the debug variable to "all" (eg. "set debug=all"), then you
> > turn on all debugging messages. This may be what you're looking for.
> >
> > Glenn
> >