[syslinux] Equivalent to GRUB_GFXPAYLOAD_LINUX=keep with vesamenu?

[nerdopolis]

On Thursday, March 18, 2021 11:25:18 AM EDT Gregory Bartholomew wrote:
> Just one last idea ... there is a "fb" kernel parameter which is supposed
> to enable the framebuffer device:
> 
> https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html#:~:text=The%20frame%20buffer%20device%20is%20enabled
> 
> Maybe try that?
> 
> On Thu, Mar 18, 2021 at 9:42 AM Gregory Bartholomew <
> gregory.lee.bartholomew at gmail.com> wrote:
> 
> > On Thu, Mar 18, 2021 at 8:02 AM nerdopolis via Syslinux <
> > syslinux at syslinux.org> wrote:
> >
> >> On Thursday, March 18, 2021 12:58:46 AM EDT Gregory Bartholomew wrote:
> >> > On Wed, Mar 17, 2021 at 10:35 PM nerdopolis via Syslinux <
> >> > syslinux at syslinux.org> wrote:
> >> >
> >> > > ...
> >> > > OK, I am realizing that in syslinux there IS a special case for
> >> > > vga=current / vga=
> >> > >
> >> > >
> >> https://repo.or.cz/syslinux.git/blob/346d2278e23f1b9f02903506753263ad7226de58:/com32/lib/syslinux/load_linux.c#l497
> >> > >
> >> > > Trying that option I do see much different behavior. It doesn't flush
> >> the
> >> > > display, as if though going into text mode (which is a good start),
> >> but it
> >> > > appears The kernel never creates the /dev/fb0 device like it does
> >> with grub
> >> > > starting it.
> >> > > ...
> >> > >
> >> >
> >> > From
> >> >
> >> https://github.com/torvalds/linux/blob/master/Documentation/fb/vesafb.rst
> >> :
> >> >
> >> > " ... 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. ..."
> >> >
> >> > I wonder if the kernel is falling back to text mode because it doesn't
> >> > recognize "vga=current" as a graphics mode? Maybe you can force it with
> >> > "video=vesafb:on" (or maybe "video=efifb:on" if you are using
> >> syslinux.efi).
> >> >
> >> I tried the VGA option as hex, and as =current, so it might not be the
> >> kernel
> >> not recognizing it, but I wonder if I am missing something in the dmesg
> >> output...
> >>
> >> I tried video=vesafb:on and that doesn't seem to work
> >> BTW: I am using isolinux.bin
> >>
> >> ...
> >
> >
> > Sorry, I'm down to just random things to try at this point, but maybe try
> > substituting "uvesafb" for "vesafb". Or maybe try "rd.driver.pre=uvesafb"
> > instead of "video=...". I'm really out of ideas at this point. Sorry. I
> > think you just need to get the right kernel module to load to get the
> > /dev/fb0 device to show up. Let us know if you figure it out.
> >
> 

Thanks for the assistance and ideas, unfortunately that doesn't seem to work. 
Seems I also need to add the user mode component for uvesafb for that to work.

And uvesafb might not work with SimpleDRM, which is a possible upcoming kernel
module that relies on firmware framebuffers for fallback modesetting, which is
why I am pursuing trying to get the framebuffer working in a generic way, to
accommodate for this possibility

Although for case of experiment, on the GRUB install, I tried to uncomment the
GRUB_GFX_PAYLOAD_LINUX=keep and then boot with vga=current there and it falls 
back to text mode... ...but I do get a message about it being deprecated in 
GRUB

If there is an issue with vga=0x0f04 my ISOs still offer boot options to try
other vga= options that give a fb of a known size like 344 for 1024x768
So I have a fallback if the automatic way doesn't work

Thanks!

Intersting.