Why does Installer include deprecated "vga=791" in grub.cfg?

[Fitzcarraldo]

This is something I've been curious about for a long time, and have finally got around to posting following my latest installation of SL10 64-bit Xfce (this time onto someone's Acer Aspire 5536-635G25Mn laptop).

The SL Installer installed a grub.cfg that included the following comment:

if loadfont $font ; then
set gfxmode=1024x768
load_video
# vga= is deprecated, grub2 handles this just fine
# making grub2 res == linux fb res
set gfxpayload=keep
insmod gfxterm
fi

and yet the kernel boot line in that file was:

linux /kernel-genkernel-x86_64-3.5.0-sabayon ro init=/linuxrc splash=silent,theme:sabayon video=vesafb:ywrap,mtrr:3 vga=791 gfxpayload=1024x768x16 console=tty1 quiet dokeymap keymap=uk domdadm resume=swap:UUID=21d41eeb-fdbb-4722-a766-00f64b857ef6 real_resume=UUID=21d41eeb-fdbb-4722-a766-00f64b857ef6 root=UUID=fd1b4e08-fc28-4a2b-898a-a729887ea756 docrypt

If "vga=" is deprecated in GRUB 2, why does the SL Installer add it in the kernel boot line? Or to put the question another way, why have the SL developers not changed the SL Installer's code or files so as to not add the "vga=791" in grub.cfg? Is there a specific reason why it has been left in? I'd be interested to hear from the developer responsible (lxnay?).

[lxnay]

Because vga= is still required for a majority of computers, still. Especially laptops or non-UEFI systems.

[Fitzcarraldo]

Doesn't the "gfxpayload=1024x768x16" replace (supersede) the "vga=791" in the case of all recent kernels, though?

http://en.wikipedia.org/wiki/VESA_BIOS_ ... de_numbers

791 means "1024x768 resolution with 16-bit colour", which is what the gfxpayload=1024x768x16 parameter is telling the kernel to use anyway. The kernel processes the gfxpayload command, so why does the command have to be repeated via a deprecated parameter? Or are two different kernel configuration parameters (drivers) being serviced by "gfxpayload=" and "vga="? If yes, which are the two different kernel configuration parameters (drivers) that those two kernel boot parameters are servicing?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
EDIT (00:16 December 6, 2012):

This is another reason why I find the inclusion of the two boot parameters in the kernel boot line in grub.cfg strange:

http://www.gnu.org/software/grub/manual ... gfxpayload

13.1.9 gfxpayload

If this variable is set, it controls the video mode in which the Linux kernel starts up, replacing the ‘vga=’ boot option. It may be set to ‘text’ to force the Linux kernel to boot in normal text mode, ‘keep’ to preserve the graphics mode set using ‘gfxmode’, or any of the permitted values for ‘gfxmode’ to set a particular graphics mode.

Depending on your kernel, your distribution, your graphics card, and the phase of the moon, note that using this option may cause GNU/Linux to suffer from various display problems, particularly during the early part of the boot sequence. If you have problems, set this variable to ‘text’ and GRUB will tell Linux to boot in normal text mode.

The default is platform-specific. On platforms with a native text mode (such as PC BIOS platforms), the default is ‘text’. Otherwise the default may be ‘auto’ or a specific video mode.

This variable is often set by ‘GRUB_GFXPAYLOAD_LINUX’.

What is parsing the "gfxpayload=1024x768x16" in the kernel boot line in grub.cfg? GRUB 2 or the kernel? If GRUB 2 is parsing the kernel boot line, the GRUB 2 manual appears to be stating that "gfxpayload=1024x768x16" replaces the deprecated "vga=791" parameter. If the kernel is parsing the kernel boot line, which driver (kernel config parameter) is using the "gfxpayload=1024x768x16" boot parameter and which driver (kernel config parameter) is using the "vga=791" (also 1024x768x16) boot parameter?

[Fitzcarraldo]

http://cateee.net/lkddb/web-lkddb/FB_BO ... PPORT.html

CONFIG_FB_BOOT_VESA_SUPPORT
If true, at least one selected framebuffer driver can take advantage of VESA video modes set at an early boot stage via the vga= parameter.

CONFIG_FB_VISA
This is the frame buffer device driver for generic VESA 2.0 compliant graphic cards. The older VESA 1.2 cards are not supported.

vga=791 is passed to the vesafb driver if you set CONFIG_FB_BOOT_VESA_SUPPORT=y and CONFIG_FB_VESA=y when building the kernel (which lxnay did for the SL kernel).

What is vesafb?
===============

This is a generic driver for a graphic framebuffer on intel boxes.

How to use it?
==============

Switching modes is done using the vga=... boot parameter. Read
Documentation/svga.txt for details.

You should compile in both vgacon (for text mode) and vesafb (for
graphics mode). Which of them takes over the console depends on
whenever the specified mode is text or graphics.

As I asked in my previous post, which kernel configuration parameter does the "gfxpayload=1024x768x16" in the kernel boot line correspond to? To which driver is "gfxpayload=1024x768x16" passed?

[steffie]

Very good question i think Fitz.....

Ps.:when i unc. the "if..fi" things in the bottom of my grub.conf my machine Z68 / I2500K / GTX550 will not boot.....
also "grub2-mkconfig -o /boot/grub2/grub.cfg" dont work because its /boot/grub/...

cu, stephan

[Fitzcarraldo]

also "grub2-mkconfig -o /boot/grub2/grub.cfg" dont work because its /boot/grub/...

That's a separate issue, though, Stephan. It's simply that lxnay decided to stick with the /boot/grub/ directory when he migrated SL from GRUB Legacy to GRUB 2. You just need to use the command "grub2-mkconfig -o /boot/grub/grub.cfg" (or "grub-mkconfig -o /boot/grub/grub.cfg", as grub-mkconfig is symlinked to grub2-mkconfig) instead of the Gentoo way, which is "grub2-mkconfig -o /boot/grub2/grub.cfg".

[lxnay]

The problem is that upstream love breaking stuff while we don't. Originally, grub2 ebuild was doing stuff into /boot/grub and then only God knows why they decided to break compatibility and have the bootdir into /boot/grub2.
If we do this NOW in Sabayon, every single machine will stop working.

Upstream Gentoo, I am talking to you, seriously, what the hell???

[Fitzcarraldo]

Moving back on topic, though, could you tell me please which kernel configuration parameter the "gfxpayload=1024x768x16" in the kernel boot line corresponds to, and to which driver "gfxpayload=1024x768x16" is passed?

[micia]

I haven't actually found any documentation to support this claim, but I think that the gfxpayload option is just an abstraction layer offered by GRUB to avoid specifying exactly the VGA code of your resolution (basically it does the same job as vga but with a different syntax).
It should also help with KMS, by offering the keep option to avoid mode switching during boot and offering facilities to change the video mode directly from /etc/default/grub (GRUB_GFXMODE and GRUB_GFXPAYLOAD_LINUX if memory serves me right), but the same holds true if vga is used in GRUB_CMDLINE_LINUX entries.

[Fitzcarraldo]

It's possible. But what I'm really trying to fathom is why SL has "gfxpayload=1024x768x16" in the kernel boot line at all. In the grub.cfg of the Gentoo installation on my main laptop, the gfxpayload commands for each kernel image are located elsewhere in the grub.cfg file, not in the linux boot line, if I specify GRUB_GFXPAYLOAD_LINUX=1024x768 in /etc/default/grub and run the grub2-mkconfig command. See the lines highlighted red in my grub.cfg listed below.

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub2-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
load_env
fi
set default="0"

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function load_video {
insmod vbe
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos6'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos6 --hint-efi=hd0,msdos6 --hint-baremetal=ahci0,msdos6 9db2f668-a682-4d6f-abc5-ed6f6c515b95
else
search --no-floppy --fs-uuid --set=root 9db2f668-a682-4d6f-abc5-ed6f6c515b95
fi
font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=1024x768
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_GB
insmod gettext
fi
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
insmod png
background_image -m stretch /grub2/mybackground.png
if sleep --interruptible 0 ; then
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Gentoo GNU/Linux' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.6.1-gentoo ...'
linux /kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/sda6 ro BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.6.1-gentoo
}
submenu 'Advanced options for Gentoo GNU/Linux' $menuentry_id_option 'gnulinux-advanced-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.6.1-gentoo' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.6.1-gentoo-advanced-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.6.1-gentoo ...'
linux /kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/sda6 ro BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.6.1-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.6.1-gentoo (recovery mode)' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.6.1-gentoo-recovery-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.6.1-gentoo ...'
linux /kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/sda6 ro single BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.6.1-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.6.0-gentoo' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.6.0-gentoo-advanced-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.6.0-gentoo ...'
linux /kernel-genkernel-x86_64-3.6.0-gentoo root=/dev/sda6 ro BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.6.0-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.6.0-gentoo (recovery mode)' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.6.0-gentoo-recovery-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.6.0-gentoo ...'
linux /kernel-genkernel-x86_64-3.6.0-gentoo root=/dev/sda6 ro single BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.6.0-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.5.4-gentoo' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.5.4-gentoo-advanced-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.5.4-gentoo ...'
linux /kernel-genkernel-x86_64-3.5.4-gentoo root=/dev/sda6 ro BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.5.4-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.5.4-gentoo (recovery mode)' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.5.4-gentoo-recovery-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.5.4-gentoo ...'
linux /kernel-genkernel-x86_64-3.5.4-gentoo root=/dev/sda6 ro single BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.5.4-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.3.5-gentoo' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.3.5-gentoo-advanced-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.3.5-gentoo ...'
linux /kernel-genkernel-x86_64-3.3.5-gentoo root=/dev/sda6 ro BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.3.5-gentoo
}
menuentry 'Gentoo GNU/Linux, with Linux x86_64-3.3.5-gentoo (recovery mode)' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-x86_64-3.3.5-gentoo-recovery-9db2f668-a682-4d6f-abc5-ed6f6c515b95' {
load_video
set gfxpayload=1024x768
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 597e8c88-8d50-443f-ae19-f510844f5d4e
else
search --no-floppy --fs-uuid --set=root 597e8c88-8d50-443f-ae19-f510844f5d4e
fi
echo 'Loading Linux x86_64-3.3.5-gentoo ...'
linux /kernel-genkernel-x86_64-3.3.5-gentoo root=/dev/sda6 ro single BOOT_IMAGE=/kernel-genkernel-x86_64-3.6.1-gentoo root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off
echo 'Loading initial ramdisk ...'
initrd /initramfs-genkernel-x86_64-3.3.5-gentoo
}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry 'Windows 7 (loader) (on /dev/sda1)' --class windows --class os $menuentry_id_option 'osprober-chain-A6863E9F863E7043' {
insmod part_msdos
insmod ntfs
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 A6863E9F863E7043
else
search --no-floppy --fs-uuid --set=root A6863E9F863E7043
fi
chainloader +1
}
menuentry 'Windows 7 (loader) (on /dev/sda2)' --class windows --class os $menuentry_id_option 'osprober-chain-A2243DA8243D7FF9' {
insmod part_msdos
insmod ntfs
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 A2243DA8243D7FF9
else
search --no-floppy --fs-uuid --set=root A2243DA8243D7FF9
fi
chainloader +1
}
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

If GRUB_GFXPAYLOAD_LINUX=1024x768 does not cause "gfxpayload=1024x768x16" to be inserted in the kernel boot line when grub2-mkconfig is run, I assume it was inserted in the kernel boot line because the SL Installer included it in GRUB_CMDLINE_LINUX in either /etc/default/grub or /etc/default/sabayon-grub (or whatever the SL file is called; I don't have access to a machine running SL for the next couple of weeks). Can you please have a look in /etc/default/grub and /etc/default/sabayon-grub to see if either specifies "gfxpayload=1024x768x16" to be in the kernel boot line, which would mean that the SL Installer did that, not GRUB 2. If GRUB 2 is indeed parsing a gfxpayload command that is not in the kernel boot line in my grub.cfg file and is passing the appropriate graphics mode to the loaded kernel (to vesafb?) then why does SL include it in the kernel boot line?