Re: [PATCH] Re: crc32 and lib.a (was Re: [PATCH] nbd in 2.5.3 does

[David Woodhouse <dwmw2@infradead.org>]

axboe@suse.de said:
>  You can do even more than this -- I dunno what I/O interface these
> embedded system generally uses (the mtd stuff?). Provided you provide
> a direct make_request_fn entry into these instead of using the queue,
> you can basically cut all of ll_rw_blk.c and elevator.c. 

We don't even do that - look at jffs2_read_super(). The only reason it even 
_looks_ like we're using a block device is because it was the easiest way 
to arrange mounting. We only allow you to mount the 'mtdblock' device, 
which isn't actually used - all we do is use the minor number to look up 
the real underlying MTD device. The dependency on _any_ of the block code 
isn't real - I can fix it as soon as there's an incentive to do so (like 
CONFIG_BLK_DEV).

> ll_rw_block, submit_bh, and generic_make_request would be all that is left. 

Those can go too. Likewise page->buffers.

>  That should reclaim quite a lot of space. If there's any interest in
> this (has it already been done?), I can help out getting it done.

I had a go once. Long enough ago that it's probably not worth trying to find
it again. I'd suggest a boolean like CONFIG_BUFFER_CACHE which does the
really intrusive stuff like removing page->buffers, and CONFIG_BLK_DEV which
can be modular (if CONFIG_BUFFER_CACHE is on), and which controls
compilation of everything in drivers/block/ and fs/block_dev.c

--
dwmw2