NetBSD Problem Report #57541

From  Mon Jul 24 07:47:58 2023
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Date: Mon, 24 Jul 2023 07:47:27 +0000 (UTC)
Subject: MI/x86 efiboot: gop command confuses raster console output
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>Number:         57541
>Category:       misc
>Synopsis:       MI/x86 efiboot: gop command confuses raster console output
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 24 07:50:00 +0000 2023
>Originator:     Rin Okuyama
>Release:        10.99.3 and release branches
Internet Initiative Japan Inc.
NetBSD netbsd 10.99.3 NetBSD 10.99.3 (AMD64_NET_MPSAFE) #1: Thu May 25 19:17:12 JST 2023  rin@latipes:/build/src/sys/arch/amd64/compile/AMD64_NET_MPSAFE amd64 x86_64
For x86 and MI (aarch64 at least) efiboot, raster console output (by
SimpleTextOutputProtocol) is corrupted by changing resolution with
gop command. Output to console apparently does not catch up with
resolution change, which results in:

- part of text is not displayed
- system freezes after some invisible output (due to out-of-bounds
  write to framebuffer?)
(1) Boot x86 or aarch64 machines with UEFI and raster console.
(2) Drop to booter prompt and change resolution by gop command
    (to small resolution typically).
(3) Some output to raster console.
Not known.

At a glance of other EFI booters with GOP support (FreeBSD and
GRUB), they seem to use their own raster console routines instead
of SimpleTextOutputProtocol, but it seems too much for me.

A trivial workaround is:
(a) Let gop command just select resolution mode.
(b) Do real resolution change just before jump to kernel.

This works just fine, except that user cannot confirm appearance
of console in efiboot...

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