[Bug 253733] vesa.ko: Invalid BIOS call when resuming from S3 suspend/sleep causes nvidia driver hang

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253733

            Bug ID: 253733
           Summary: vesa.ko: Invalid BIOS call when resuming from S3
                    suspend/sleep causes nvidia driver hang
           Product: Base System
           Version: 12.2-RELEASE
          Hardware: amd64
                OS: Any
            Status: New
          Severity: Affects Many People
          Priority: ---
         Component: kern
          Assignee: bugs at FreeBSD.org
          Reporter: sblachmann at gmail.com

In vesa.ko there is a function that gets called when resuming from sleep, e.g.
at resuming after S3 suspend via 'zzz'.
This function does a BIOS call, which is related to restoring the graphics
cards' previous state it had before powering off.

On Nvidia cards this BIOS function seems to be implemented in a different way
than on most other cards.
For this reason, calling this BIOS function causes the Nvidia graphics driver
to hang, failing to resume.
(For technical background, read my discussion with jkim in PR 224069:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224069 )

Reproducing the bug is easy:
-Install FreeBSD (eg using GENERIC kernel).
-Enable sc (kern.vty="sc" in /boot/loader.conf).
-Install xorg. Install and configure nvidia driver. Reboot and start xorg via
startx.
-Enter "zzz" in a xterm.
-Watch the system/driver hang, keyboard (PS/2) and mouse becoming unresponsive
when attempting to switch back to graphics mode.
-Hitting the power button results no visible change, until after timeout a
message about an unresponsive stop job (presumably the nvidia driver) appears
shortly before powering off.

For reproducing the bug it is essential to use GENERIC kernel!
Because, working around by building and installing a custom kernel without
"options VESA" fixes the hang after suspend/resume. It is also important to not
have vt and its helper modules (vt_efifb etc) in the kernel, as these pull in
the vesa.ko showstopper module.

Already back in 2017 I found that skipping (commenting out) the Nvidia BIOS
call fixes the issue, making resume work reliably.

So I believe the proper fix would be:
1. check whether the graphics card is Nvidia
2. if it is Nvidia, skip that BIOS call in /usr/src/sys/dev/fb/vesa.c line 520.

Pseudocode for a patch might look like this:

(+)if (! nvidia_card_is_installed) {
x86bios_intr(&regs, 0x10);
(+)}


Side note:
All my systems use the sc console, not the vt console.
So I do not know the system behaviour when using vt.
Thus please use sc in text mode when reproducing the bug!

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