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From: sthaug@nethelp.no
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Subject: Problems detecting ATAPI CDROM in 2.2-970801-RELENG
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Date: Sun, 17 Aug 1997 22:41:10 +0200
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I recently upgraded a machine here from 2.2-BETA (as of 961226) to 
2.2-970801-RELENG. This broke the detection of an ATAPI CDROM on wdc1.
Further checking (by adding kernel printf's to sys/i386/isa/wd.c) showed
that the problem is in wdprobe(). If I add a printf just before line 340
of wd.c (version 1.119.2.6):

	printf("XXX %s%d get errstatus\n", dvp->id_driver->name, unit);
	du->dk_error = inb(du->dk_port + wd_error);

the CDROM is detected just fine. If I revert to the original wd.c, the
CDROM is not detected.

Obviously there's a timing issue here, and the printf adds enough of a
delay that the detection works. However, as far as I can see both wdprobe
and wdcommand (which is called just before my printf) are exactly the same
in 2.2-BETA and 2.2-970801-RELENG.

Any good ideas?

Steinar Haug, Nethelp consulting, sthaug@nethelp.no