Bug#926539: rootskel: steal-ctty no longer works on at least sparc64

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Control: reassign -1 src:linux
Control: tags -1 patch

On 4/16/19 1:16 PM, Ben Hutchings wrote:
>> Do you think we could carry a patch in src:linux for the time being?
> [...]
> 
> I would rather not do that until it's accepted, as if it that doesn't
> happen we either have to switch back or carry it forever.

My patch has been merged upstream now and is planned for -stable [1].

Attaching the patch.

Adrian

> [1] https://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc.git/commit/?id=07a6d63eb1b54b5fb38092780fe618dfe1d96e23

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

>From 0d7bc2b2fbdfeb58a06371996dd8c225b6d03343 Mon Sep 17 00:00:00 2001
From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Date: Tue, 11 Jun 2019 16:54:27 +0200
Subject: [PATCH] sunhv: Fix device naming inconsistency between sunhv_console
 and sunhv_reg

In d5a2aa24, the name in struct console sunhv_console was changed from "ttyS"
to "ttyHV" while the name in struct uart_ops sunhv_pops remained unchanged.

This results in the hypervisor console device to be listed as "ttyHV0" under
/proc/consoles while the device node is still named "ttyS0":

root@osaka:~# cat /proc/consoles
ttyHV0               -W- (EC p  )    4:64
tty0                 -WU (E     )    4:1
root@osaka:~# readlink /sys/dev/char/4:64
../../devices/root/f02836f0/f0285690/tty/ttyS0
root@osaka:~#

This means that any userland code which tries to determine the name of the
device file of the hypervisor console device can not rely on the information
provided by /proc/consoles. In particular, booting current versions of debian-
installer inside a SPARC LDOM will fail with the installer unable to determine
the console device.

After renaming the device in struct uart_ops sunhv_pops to "ttyHV" as well,
the inconsistency is fixed and it is possible again to determine the name
of the device file of the hypervisor console device by reading the contents
of /proc/console:

root@osaka:~# cat /proc/consoles
ttyHV0               -W- (EC p  )    4:64
tty0                 -WU (E     )    4:1
root@osaka:~# readlink /sys/dev/char/4:64
../../devices/root/f02836f0/f0285690/tty/ttyHV0
root@osaka:~#

With this change, debian-installer works correctly when installing inside
a SPARC LDOM.
---
 drivers/tty/serial/sunhv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 63e34d868de8..f8503f8fc44e 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -397,7 +397,7 @@ static const struct uart_ops sunhv_pops = {
 static struct uart_driver sunhv_reg = {
 	.owner			= THIS_MODULE,
 	.driver_name		= "sunhv",
-	.dev_name		= "ttyS",
+	.dev_name		= "ttyHV",
 	.major			= TTY_MAJOR,
 };
 
-- 
2.21.0