Re: 64-bit capable block device layer

["Stephen C. Tweedie" <sct@redhat.com>]

Hi,

On Wed, Mar 07, 2001 at 07:53:23PM +0100, Jens Axboe wrote:
> > 
> > OTOH, I'm not sure what problems it could give to make this
> > a compile-time option...
> 
> Plus compile time options are nasty :-). It would probably make
> bigger sense to completely skip all the merging etc for low end
> machines. I think they already do this for embedded kernels (ie
> removing ll_rw_blk.c and elevator.c). That avoids most of the
> 64-bit arithmetic anyway.

It's not just a sector-number and ll_rw_blk/elevator issue.  The limit
goes all the way up to the users of the block device, be they the
filesystem, buffer cache or block read/write layer.  

This is especially true for filesystems like XFS which need a 512-byte
blocksize.  At least with ext2 you can set the blocksize to 4kB and
get some of the benefit of larger block devices without having to
overflow the 32-bit block number.

Cheers,
 Stephen