Re: The 4GB memory thing

[Andrea Arcangeli <andrea@suse.de>]

kanoj@google.engr.sgi.com (Kanoj Sarcar) writes:

> I don't see a README.gz under 
>  http://www.kernel.org/pub/linux/kernel/people/andrea/tools/apply-patches/

lftp> pwd
ftp://ftp.it.kernel.org/pub/linux/kernel/people/andrea/tools/apply-patches
lftp> ls README.gz
-rw-r--r--   1 ftp      daemon        875 Oct 25 00:43 README.gz
lftp> 

> In any case, did you a have a small technical README on how rawio works
> on bigmem in 2.2.13aa3? Btw, I haven't seen the rawio 2.2 port, I am 

As first you can have a look at the rawio patch.

        ftp://ftp.it.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.2/2.2.13aa3/z-bigmem-rawio-2.2.13aa2-1.gz

The above patch includes all the necessary stuff to make rawio working
fine on bigmem pages.

Basically the code uses regular pages as bounce buffers to do the I/O
on bigmem pages.

> assuming its very similar to 2.3 ... where brw_kiovec() refuses to 
> accept PageHighMem pages. I didn't see anything in
> z-bigmem-2.2.13aa3-7

No. The z-bigmem-rawio-2.2.13aa2-1.gz in 2.2.13aa3 allows brw_kiovec
to do I/O on bigmem pages.

> that tinkers either with fs/buffer.c.

I take the bigmem stuff separated from rawio. The rawio patch (pointed
out above) included in 2.2.13aa3 is an incremental patch that goes on the top of
bigmem. I take all the patches separated to allow everybody out there to merge
easily my stuff and to see the only related necessary changes on
topic.

-- 
Andrea
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