From: Mikael Pettersson <mikpe@csd.uu.se>
To: alan@lxorguk.ukuu.org.uk
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] arch/i386/boot/bootsect.S incompatibility problem
Date: Sat, 27 Oct 2001 16:10:59 +0200 (MET DST) [thread overview]
Message-ID: <200110271410.QAA02345@harpo.it.uu.se> (raw)
Alan,
The patch below fixes an incompatibility in arch/i386/boot/bootsect.S,
which kills Linux' floppy driver on some recent motherboards (e.g. my
new ASUS P4T-E Pentium4/I850/S478 mb).
After reading the kernel image, bootsect.S calls kill_motor to stop
the floppy drive, which it does by poking port 0x3f2. On the P4T-E,
this locks up the FDC, casing drivers/block/floppy to report:
Floppy drive(s): fd0 is 1.44M
// long delay here
floppy0: no floppy controllers found
drivers/block/floppy.c:reset_fdc() knows about different vintages of
FDCs, and uses a different method for non-antique FDCs (poking port
0x3f4 instead). If I use that method in bootsect.S, then the FDC doesn't
hang and the floppy driver can identify and use it properly.
However, instead of poking an I/O port there is a BIOS call to reset
the FDC: bootsect.S itself uses that call further up, so my patch simply
replaces the broken I/O port poke with that BIOS call. Tested on a
number of different boxes here, with no breakage observed.
/Mikael
--- linux-2.4.13-ac2/arch/i386/boot/bootsect.S.~1~ Sun Sep 23 21:06:30 2001
+++ linux-2.4.13-ac2/arch/i386/boot/bootsect.S Sat Oct 27 13:35:13 2001
@@ -395,9 +395,15 @@
# NOTE: Doesn't save %ax or %dx; do it yourself if you need to.
kill_motor:
+#if 1
+ xorw %ax, %ax # reset FDC
+ xorb %dl, %dl
+ int $0x13
+#else
movw $0x3f2, %dx
xorb %al, %al
outb %al, %dx
+#endif
ret
sectors: .word 0
reply other threads:[~2001-10-27 14:10 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200110271410.QAA02345@harpo.it.uu.se \
--to=mikpe@csd.uu.se \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).