Date: Fri, 27 Jun 1997 22:27:08 +1000 From: Bruce Evans <bde@zeta.org.au> To: abial@korin.warman.org.pl, msmith@atrad.adelaide.edu.au Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Disk built-in hw cache Message-ID: <199706271227.WAA25213@godzilla.zeta.org.au>
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>> > I just read certain discussion on Linux list concerning >> > bad/missing/removed disk cache in "repaired" (and sold as new) hard disks. >> > Linux prints during probing the size of disk cache (at least that what the >> > hd will tell it). How to achieve the same result in FreeBSD? There is a >> > #ifdef WDDEBUG flag in wd.c, around some interesting printfs. Will it give >> > me this info? >> >> Uhh, this sounds pretty bogus. Do you have a reference to anything >> authoratative on the subject? > >No :-(. AFAIR from that discussion, IDE disks answer certain query by >returning the info stored somwhere on cyl 0. How this info relates to It would probably be stored in the drive's firmware except on ancient drives. wdp_buffersize (in wdreg.h) is documented in the old draft of the ATA spec that I have (revision 4c). It is the "Buffer size in 512 byte increments (0000h=not specified)". `Buffer' doesn't seem to be specified. >The original story goes like this: those folks bought some disks, saw the >"0 kB cache" during startup, went to the seller who checked the disk with >his diagnostic proggy (it also said "0 kB cache"), and then he started The Linux ide-disk driver just prints wdp_buffersize. 0 means unspecified :-). It probably doesn't mean much. Bruce
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