Current-Users archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: Does wscons use compat syscalls to switch sessions

Yes, it sounds very familiar.

On Sun, 18 Oct 2015, Valery Ushakov wrote:

On Sun, Oct 18, 2015 at 11:03:37 +0800, Paul Goyette wrote:

I just noticed that when switching console sessions from my X display
(on ttyE4) to the console session (on ttyE0), the system auto-loads the
"compat" kernel module.

Is this expected?  normal?  Shouldn't all "current" production code be
using "current" syscalls and/or ioctls?

This might be (haven't looked) the same problem I complained about
some time ago on tech-kern:

On Sun, Dec 15, 2013 at 15:35:01 +0400, Valery Ushakov wrote:

Date: Sun, 15 Dec 2013 15:35:01 +0400
From: Valery Ushakov <>
Subject: Compat module auto-bounce

ttioctl() in sys/tty.c ends with doing

    (void)module_autoload("compat", MODULE_CLASS_ANY);

for ioctls that it doesn't know about.  This causes compat module to
auto-bounce in and out a lot.  Note that this happens even for
up-to-date userland that doesn't need compat code.  E.g. ttyname(3)
uses TIOCPTSNAME which ttioctl() doesn't handle.  Running vi on
console seems to cause compat.mod to be autoloaded twice.

This seems rather wasteful.


| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:       |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at    |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at  |

Home | Main Index | Thread Index | Old Index