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Message-ID: <20200331154908.GB24854@1wt.eu>
Date: Tue, 31 Mar 2020 17:49:08 +0200
From: Willy Tarreau <w@....eu>
To: Christoph Hellwig <hch@...radead.org>
Cc: Denis Efremov <efremov@...ux.com>, Jens Axboe <axboe@...nel.dk>,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Helge Deller <deller@....de>, Ian Molton <spyro@....com>,
Ivan Kokshaysky <ink@...assic.park.msu.ru>,
Matt Turner <mattst88@...il.com>,
Richard Henderson <rth@...ddle.net>,
Russell King <linux@...linux.org.uk>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>, x86@...nel.org
Subject: Re: [PATCH 00/23] Floppy driver cleanups
On Tue, Mar 31, 2020 at 08:28:12AM -0700, Christoph Hellwig wrote:
> On Tue, Mar 31, 2020 at 01:01:36PM +0200, Willy Tarreau wrote:
> > I'm not sure what this implies regarding this code, to be honest. It's
> > very tricky and implements sort of a state machine using function pointers
> > within its interrupt handler so you never know exactly what accesses what,
> > and quite a part of it remains obscure to me :-/ I can accept to help, I
> > can even run tests since I still have running hardware, but I'd at least
> > need some guidance. And probably Denis would know better than me there.
> > Also I doubt we'd get sufficient testing on less common archs. While I
> > do have sparc64/parisc/alpha available, I haven't booted a recent kernel
> > on any of them for a while (2.4 used to be the last ones), and I'm not
> > sure it's reasonable to go into such changes without proper testing.
>
> The basic change is that instead of using bio_data() or page_address
> all pages coming from the block layer need to be properly kmap()ed.
> I'll try to cook something up an will send it to Denis and you for
> review and testing. The code things about sparc64/parisc/alpha is
> that they all don't have highmem, so these changes should be effective
> no-ops for them.
OK, thanks for the explanation!
Willy
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