Re: Grub2 almost does what I want

[Felix Miata]

On 2013-02-07 15:50 (GMT-0800) Jordan Uggla composed:

> Felix Miata wrote:

> > If it wasn't already there or available, how could a user edit cmdline at
> > boot time to delete it or change it to something temporarily preferable?

> They wouldn't edit the linux cmdline, they would add "gfxpayload=foo"
> (on its own line).

They maybe, not me:

# lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 82865G Integrated Graphics 
Controller (rev 02)

# cat /etc/os-release | grep ETTY
PRETTY_NAME="Mageia 3"

# rpm -qa | grep grub2
grub2-2.00-17.mga3

# ll /boot/grub2/i386-pc/core*
-rw-r--r-- 1 root root 26473 Feb  4 17:36 /boot/grub2/i386-pc/core.img

# cat /disks/realboot/grub/menu.lst | grep core.img
kernel (hd0,21)/boot/grub2/i386-pc/core.img

## BEGIN GRUB2 TEST BOOT ##

From (hd0,msdos22)/boot/grub/grub.cfg @ 
http://fm.no-ip.com/Tmp/Linux/Mdv/grub.cfg.04 I selected

        menuentry 'Mageia GNU/Linux, with Linux cur'

to edit, and the Grub 2.00 edit screen when I finished editing looked like:

        set gfxpayload=text
        insmod gzio
        insmod part_msdos
        insmod ext2
        set root='hd0,msdos22'
        linux   /boot/vmlinuz root=/dev/hda22 ro noplymouth splash=verbose 
nomodeset vga=794 3
        initrd  /boot/initrd

when I keyed Ctrl-X.

# uname -r
3.8.0-desktop-0.rc5.1.mga3

# mount | grep "on / type"
/dev/hda22 on / type ext3 
(rw,noatime,errors=continue,user_xattr,acl,barrier=1,data=ordered)

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-cur root=/dev/hda22 ro noplymouth splash=verbose 
nomodeset vga=794 3

# stty -a | grep rows
speed 38400 baud; rows 64; columns 160; line = 0;

## END GRUB2 TEST BOOT ##

Of course it is much simpler when just booting the default kernel/initrd 
directly via the
(openSUSE Grub Legacy's GFXboot) master bootloader:

title Mageia Cauldron default kernel on sda22
    root (hd0,21)
    kernel /boot/vmlinuz root=LABEL=22cauldrn noresume splash=verbose vga=794 
address@hidden 3
    initrd /boot/initrd

that highlights the active selection but leaves cursor at end of kernel cmdline 
waiting for edits,
where to match the above test boot I'd s/address@hidden/nomodeset/ before 
proceeding to again
find included in /proc/cmdline the string vga=794. Maybe now you can see when I write 
"cmdline"
I'm referring to anything that results in inclusion in the file /proc/cmdline 
regardless whether
"on its own line" in the process. I don't see the need for "on its own line" in 
order to reach
/proc/cmdline any more than I do for the deprecation message about the still 
and for as long as
gfxchips without KMS support exist quite useful vga= cmdline option.

> > Vga= for such chips does still do what it did
> > pre-KMS. As long as kernels still respond to it, people don't need
> > deprecation warnings from their boot loader about a kernel video function.

> The kernel does not respond to it, and never has. It has always been
> the bootloader that responded to it, as documented in
> https://www.kernel.org/doc/Documentation/kernel-parameters.txt .

So what you're saying is that a boot loader after accepting a menu selection 
from the user
is altering the video mode prior to loading the kernel and initrd? What 
business is this
for a boot loader? I sounds like a Trojan vector to me, and even if not, a way 
to swell
the boot loader code beyond available space to install it. Does Lilo produce 
such a message?
Syslinux? AiR-Boot?

> > How nice it is (not) to have new "improved" versions of init systems and
> > boot loaders tell us we must change to using cmdline options or similarly
> > obtuse configuration options that require 2-10 times as much typing and
> > recollection power to perform same function as required in the past.
> > 1024x768x24 may be a bit easier for n00bs to wrap their brains around, but
> > it's not helpful to those of us who learned what vga= itself referred to and
> > what relevant vga= options meant last century and who prefer less typing to
> > more typing.

> Yes, gfxmode=1024x768x24 takes more typing than "vga=792". That is true.

So why not video=, same as the kernel uses, not to be confused with any mode 
specified
for X? Gfx is about graphic effects, not expected in the production of vtty 
text.

> > And it's certainly not welcome without adding desirable new
> > function in the process to consume more of the precious resource that is the
> > kernel cmdline.

> I don't understand this comment.

Try to put more than 254 chars or whatever the limit is on the cmdline and the 
excess is
truncated (the kernel never gets it). With a full pathname of the kernel plus a 
UUID, it
can be difficult to observe a complete cmdline statement on a single line, and 
at times,
it can be impossible to give everything needed to the kernel. That is yet 
another
instance of bloat (more content than required to do its job).
--
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

 Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/