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Message-ID: <ad4e561c-1d49-4f25-882c-7a36c6b1b5c0@draconx.ca>
Date: Wed, 29 May 2024 00:45:56 -0400
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To: linux-kernel@vger.kernel.org,
 Linux regressions mailing list <regressions@lists.linux.dev>
Cc: Alexey Gladkov <legion@kernel.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
From: Nick Bowler <nbowler@draconx.ca>
Subject: PROBLEM: kbd busted in linux 6.10-rc1 (regression)
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Hi,

It seems kbd utilities are all broken on linux 6.10-rc1.  For example:

   # loadkeys en-latin9
   Couldn't get a file descriptor referring to the console.
   [and it did not change the console keymap]

This is a regression from linux 6.9.  If I run strace on a working
kernel, at the point of the first difference we see:

   openat(AT_FDCWD, "/dev/tty0", O_RDWR)   = 3
   ioctl(3, TCGETS, {c_iflag=BRKINT|ICRNL|IXON|IMAXBEL|IUTF8, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|OPOST|ONLCR, c_cflag=B38400|CS8|CREAD|HUPCL, c_lflag=, ...}) = 0
   ioctl(3, KDGKBTYPE, [KB_101])           = 0
   ...

On a busted kernel, we get:

   openat(AT_FDCWD, "/dev/tty0", O_RDWR)   = 3
   ioctl(3, TCGETS, {c_iflag=IUTF8, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|OPOST|ONLCR, c_cflag=B38400|CS8|CREAD|HUPCL, c_lflag=, ...}) = 0
   ioctl(3, KDGKBTYPE, 0xffceaebb)         = -1 ENOTTY (Inappropriate ioctl for device)
   close(3)                                = 0
   ...

A very similar problem occurs with kbd_mode, chvt, etc.

Bisection implicates the following:

   8c467f3300591a206fa8dcc6988d768910799872 is the first bad commit
   commit 8c467f3300591a206fa8dcc6988d768910799872
   Author: Alexey Gladkov <legion@kernel.org>
   Date:   Wed Apr 17 19:37:35 2024 +0200
   
       VT: Use macros to define ioctls
   
       All other headers use _IOC() macros to describe ioctls for a long time
       now. This header is stuck in the last century.
   
       Simply use the _IO() macro. No other changes.
   
       Signed-off-by: Alexey Gladkov <legion@kernel.org>
       Link: https://lore.kernel.org/r/e4229fe2933a003341e338b558ab1ea8b63a51f6.1713375378.git.legion@kernel.org
       Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reverting this commit corrects the issue.

This testing was done on my sparc system in case it matters.

Let me know if you need any more info!

Thanks,
  Nick