Date: Thu, 21 Feb 2008 16:37:35 +0200 From: Andriy Gapon <avg@icyb.net.ua> To: Bruce Evans <brde@optusnet.com.au> Cc: freebsd-fs@freebsd.org, freebsd-current@freebsd.org, freebsd-geom@freebsd.org Subject: Re: newfs_msdos and dvd-ram (fwsectors, fwheads) Message-ID: <47BD8CAF.9090908@icyb.net.ua> In-Reply-To: <20080222005213.W5655@besplex.bde.org> References: <47B81D07.7090208@icyb.net.ua> <47BD6F39.7080105@icyb.net.ua> <20080222005213.W5655@besplex.bde.org>
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on 21/02/2008 16:27 Bruce Evans said the following: > On Thu, 21 Feb 2008, Andriy Gapon wrote: > >> on 17/02/2008 13:39 Andriy Gapon said the following: >>> Should newfs_msdos be able to work on "whole" cdX/acdX device ? >>> [ufs/ffs] newfs can do it. >>> But with newfs_msdos I had to run disklabel first and then I could >>> create a filesystem on cdXa, but I couldn't do it on the whole disk. >> It seems that the reason for this newfs_msdos behavior is in the >> following lines: >> if (ioctl(fd, DIOCGSECTORSIZE, &dlp.d_secsize) == -1) >> errx(1, "Cannot get sector size, %s", strerror(errno)); >> if (ioctl(fd, DIOCGFWSECTORS, &dlp.d_nsectors) == -1) >> errx(1, "Cannot get number of sectors, %s", strerror(errno)); >> if (ioctl(fd, DIOCGFWHEADS, &dlp.d_ntracks)== -1) >> errx(1, "Cannot get number of heads, %s", strerror(errno)); >> >> While a failure to get sector size is a serious situation indeed, number >> of sectors per track and number of heads are just relics of the past and >> are not applicable to all types of should-be-supported media. >> What's even more funny is that those values can be set via command line >> options and in that case values from ioctl are not used at all. > > Also, it needs the BIOS geometry, but has been broken to ask for, and Bruce, you lost me after this. I understand that you speak about a general case, but is there a "BIOS geometry" for DVD-RAM disk ? Would any information about physical structure of DVD-RAM disk prove useful for FAT on it ? I thought that all those CHS parameters were useful only in times when CHS was the disk access mode (and maybe for performance optimizations). I don't see how those parameters can be of any real use now. P.S. I must declare that I know zero about FAT. -- Andriy Gapon
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