Date: 09 Jan 2002 16:12:49 -0500 From: Randell Jesup <rjesup@wgate.com> To: hackers@FreeBSD.ORG Subject: Re: FreeBSD Floppy driver needs enhancement... Message-ID: <7dcbb25c031dc107d2@[192.168.1.4]>
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Terry Lambert <tlambert2@mindspring.com> writes: >Julian Stacey wrote: >> Doubtless some will have bad sectors by now. Here's a rescue tool: >> http://bim.bsn.com/~jhs/src/bsd/jhs/bin/public/valid/valid.c & v= alid.1 >> >> `Valid' runs on FreeBSD, but only rescues when running on MSDOS ! >> (because read() on DOS3.2 returns the intact buffer even if the >> CRC fails, so I can then average each bit of each byte in each >> sector for all reads). `Valid' works at sector level, no knowledge >> of file systems, so it can rescue/ manipulate BSD FS sectors on >> floppy, tar images, DOS or Minix file systems etc. > >Sounds like the FreeBSD floppy driver needs to be modified to >return the full buffer, even if there is a CRC error. > >This implies a descriptor being passed, so that the CRC and >the data are seperate. > >You could probably just wadd an ioctl that expected the >descriptor to be at the front of a data buffer, so that >you passed the address of the descriptor + buffer, after >the ioctl(). > >This seems a useful feature... Yes (if anyone still cares about floppies). The old Amiga trackdisk (floppy driver) could do that, since all the decoding was in software (and via the graphics bitblitter(!)). Do the integrated disk controllers in PC's (still) allow direct raw bit access, or only after MFM decoding? Also, I seem to remember PC's can't recover from bad sector ID's= . If I remember correctly, you can read uncorrected sectors off of ATA (maybe) and SCSI (I think), at least using CAM. Quite honestly, I can see some use for this in HD's; I don't see much use for it in floppies, except maybe for HD-less servers like gnat box= es. -- Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team rjesup@wgate.com "They that can give up essential liberty to obtain a little temporary safet= y deserve neither liberty nor safety." -Benjamin Franklin, Historical Review of Pennsylvania, 1759. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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