[patch] 4GB I/O, cut three

[Jens Axboe <axboe@kernel.org>]

Hi,

Another day, another version.

Bugs fixed in this version: none
Known bugs in this version: none

In other words, it's perfect of course.

Changes:

- Added ide-dma segment coalescing
- Only print highmem I/O enable info when HIGHMEM is actually set

Please give it a test spin, especially if you have 1GB of RAM or more.
You should see something like this when booting:

hda: enabling highmem I/O
...
SCSI: channel 0, id 0: enabling highmem I/O

depending on drive configuration etc.

Plea to maintainers of the different architectures: could you please add
the arch parts to support this? This includes:

- memory zoning at init time
- page_to_bus
- pci_map_page / pci_unmap_page
- set_bh_sg
- KM_BH_IRQ (for HIGHMEM archs)

I think that's it, feel free to send me questions and (even better)
patches.

-- 
Jens Axboe