Date: Sun, 06 Feb 2000 00:19:50 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Warner Losh <imp@village.org> Cc: hackers@FreeBSD.org Subject: RE: Question about msdosfs Message-ID: <200002060519.AAA40733@server.baldwin.cx> In-Reply-To: <200002050626.XAA03255@harmony.village.org>
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On 05-Feb-00 Warner Losh wrote:
>
> In msdosfs_vfsops.c we have:
> || !pmp->pm_Heads || pmp->pm_Heads > 255
>#ifdef PC98
> || !pmp->pm_SecPerTrack || pmp->pm_SecPerTrack > 255) {
>#else
> || !pmp->pm_SecPerTrack || pmp->pm_SecPerTrack > 63) {
>#endif
> error = EINVAL;
>
> What's so special about 63? Many scsi drives have more than 63
> sectors per track. The only reason that we don't see problems with
> this is that it appears that CAM appears to be using a geometry with
> 64 heads and 32 sectors and N cylendars. What's the justification
> here?
The PC BIOS (int 0x13 calls) only allows for 63 sectors numbered 1-63 for each
track (cylinder). That is most likely the reason for the 63.
> Warner
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
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