Re: Support for 4KB sectors size disk ?

[David Holland <dholland-current%netbsd.org@localhost>]

On Wed, Jan 13, 2010 at 08:43:34PM +0900, Izumi Tsutsui wrote:
 > > Note that, even if the bios does 2k/4k reads, the i386 initial
 > > boot sequence will still work. Although the transfers will be
 > > longer than expected they won't overwrite anything important.
 > > The fs specific code will need to transfer the correct number of
 > > bytes - but it has more code space and is reading file system
 > > blocks, not disk sectors.
 > 
 > FFS structures might also depends on I/O implementation of the kernel.

FFS knows about the hardware blocksize so it can make sure directory
entries don't span block boundaries. (This prevents getting partial
updates after a crash, assuming hardware block writes are atomic.) I
don't know enough about FFS internals to be sure at this point whether
this size should stay 512 or not. One would like FS images to continue
to work if dd'd to a disk with smaller blocks.

-- 
David A. Holland
dholland%netbsd.org@localhost