From 0b9cf3aa6b1e934807b40b4d478d7e11f7c43f55 Mon Sep 17 00:00:00 2001 From: Roland Kletzing Date: Wed, 23 Jul 2008 21:31:10 -0700 Subject: [PATCH] mdacon messing up default vc's - set default to vc13-16 again mdacon incorrectly detects MDA hardware on systems without such graphics card. One may load this module by chance, for example when doing some systematical module-testing, and if there is no Monochrome Display Adapter attached , module init renders vc1-16 completely unusable. I and others have run into this more than once. see [Bug 224522 - modprobe mdacon freezes machine -> https://bugzilla.novell.com/show_bug.cgi?id=224522 ] for example Apparently proper MDA detection seems to be broken for a long time - seems to be related to those #ifdef TEST_MDA_B statements added by Edward Betts. this commit back in 2002 made things even worse : http://git.kernel.org/?p=linux/kernel/git/tglx/history.git;a=commit;h=c72757b49c88914433244757fb4967fc63546685 It changed default vc allocation from 13-16 to 1-16 for no apparent reason (!?) , and with that (and without X), mdacon grabs the vc you`re currently sitting on and locks you out. this is from Kconfig : >config MDA_CONSOLE > depends on !M68K && !PARISC && ISA > tristate "MDA text console (dual-headed) (EXPERIMENTAL)" > ---help--- > Say Y here if you have an old MDA or monochrome Hercules graphics > adapter in your system acting as a second head ( = video card). You > will then be able to use two monitors with your Linux system. Do not > say Y here if your MDA card is the primary card in your system; the > normal VGA driver will handle it. As we can see mdacon is just meant as an additional driver for dual-head setup, and since kernel 2.4.36 still defaults to vc13-16 , setting the default back to that value again shouldn`t do any harm. Hereby i'm reverting that change, setting default back to to vc13-16 again. Besides the fact that mdacon may be rarely or never be used these days and could perhaps put to trash anyway (pre-dinosaur hardware!), indeed this is not a real solution, but at least it removes the unfortunate side-effect of messing up the vc you`re working on. Signed-off-by: Roland Kletzing Cc: James Simmons Cc: "Antonino A. Daplas" Cc: Tim Schmielau Cc: Jan Engelhardt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/console/mdacon.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/video/console/mdacon.c b/drivers/video/console/mdacon.c index 38a296bbdfc9..9901064199bd 100644 --- a/drivers/video/console/mdacon.c +++ b/drivers/video/console/mdacon.c @@ -71,13 +71,15 @@ static char *mda_type_name; /* console information */ -static int mda_first_vc = 1; +static int mda_first_vc = 13; static int mda_last_vc = 16; static struct vc_data *mda_display_fg = NULL; module_param(mda_first_vc, int, 0); +MODULE_PARM_DESC(mda_first_vc, "First virtual console. Default: 13"); module_param(mda_last_vc, int, 0); +MODULE_PARM_DESC(mda_last_vc, "Last virtual console. Default: 16"); /* MDA register values */