In article <20050216.085534.128329712.imp_at_bsdimp.com> "M. Warner Losh" <imp_at_bsdimp.com> writes: > I see. Let me see if I understand the implications: > > (1) This disk won't interoperate with other OSes on the pc98 > machine because the pc98 partition format specifies things > in terms of CHS, but doesn't specify an actual geometry. I don't test it yet, but I think it is no problem if right geometry translation is done. > (2) Further, since dp_scyl and dp_ecyl are both 16bits, we are > limited to 65535 cylinders. The above geometry of 387621 > violates this assumption. So you can really only use > 66059280 of the 390721968 sectors on this disk (or about 17%). I tried to use the disk with 16H/63S geometry but I cannot at all. It seems that the fdisk and/or disklabel write to strange place. > (3) It is insufficent to fix this in geom_pc98 because that is > not used until after the partition is placed on the disk > and fdisk_pc98 needs the geometry to place that partition. Yes. > (4) This only impacts newer ATA6 disks. ATA5 and older appear > to be working properly. ata6 disks need some other > mechanism to get this information, correct? Probably... I am sure that ATA6 disks at least need to get a geometry information from PC98 BIOS. > When I asked about the 'get the geometry from the BIOS' patches that > are circulating, I was told that it was hard to match the FreeBSD > device to the BIOS table. I think that it is hard to get a right geometry in all cases, many extended ATA cards are used, but it succeeds mostly. --- TAKAHASHI Yoshihiro <nyan_at_jp.FreeBSD.org>Received on Thu Feb 17 2005 - 07:08:47 UTC
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