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Date: Mon, 1 Dec 1997 09:10:02 -0800 (PST)
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From: Bruce Evans <bde@zeta.org.au>
Subject: Re: kern/5186: bug in diskslice_machdep.c (fix included)
Reply-To: Bruce Evans <bde@zeta.org.au>
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The following reply was made to PR kern/5186; it has been noted by GNATS.

From: Bruce Evans <bde@zeta.org.au>
To: andre.albsmeier@mchp.siemens.de, FreeBSD-gnats-submit@FreeBSD.ORG
Cc:  Subject: Re: kern/5186: bug in diskslice_machdep.c (fix included)
Date: Tue, 2 Dec 1997 03:57:25 +1100

 >        Either the code or the comment above it is wrong in sys/i386/isa/diskslice_machdep.c:
 
 They still look correct to me.
 
 >        /*
 >         * If ssector1 is on a cylinder >= 1024, then ssector can't be right.
 >         * Allow the C/H/S for it to be 1023/ntracks-1/nsectors, or correct
 >         * apart from the cylinder being reduced modulo 1024.  Always allow
 >         * 1023/255/63.
 >         */
 >        if (ssector < ssector1
 >            && ((chs_ssect == nsectors && dp->dp_shd == ntracks - 1
 >                 && chs_scyl == 1023)
 >                || (secpercyl != 0
 >                    && (ssector1 - ssector) % (1024 * secpercyl) == 0))
 >            || (dp->dp_scyl == 255 && dp->dp_shd == 255
 >                && dp->dp_ssect == 255)) {
 >
 >         Since we can't enter 255 for the number of sectors, I think it's the code.
 
 dp_ssect consists of a 6-bit sector number and the top two bits of the head
 number.  dp->ssect == 255 means sector 63, head >= 768.  In particular, it
 is 255 for 1023/255/63 geometry.
 
 Bruce