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From: David Woodhouse <dwmw2@infradead.org>
To: dedekind1@gmail.com
Cc: Mike Frysinger <vapier@gentoo.org>,
	uclinux-dev@uclinux.org, Bernd Schmidt <bernds_cb1@t-online.de>,
	David Howells <dhowells@redhat.com>,
	Paul Mundt <lethal@linux-sh.org>,
	linux-mtd@lists.infradead.org, Greg Ungerer <gerg@uclinux.org>,
	uclinux-dist-devel@blackfin.uclinux.org,
	David McCullough <davidm@snapgear.com>
Subject: Re: [PATCH 1/2] mtd: physmap: add physmap_unmapped_area() for no-mmu XIP
Date: Wed, 04 Aug 2010 10:33:28 +0100	[thread overview]
Message-ID: <1280914408.19499.8.camel@localhost> (raw)
In-Reply-To: <1276352794.19028.122.camel@localhost>

On Sat, 2010-06-12 at 17:26 +0300, Artem Bityutskiy wrote:
> On Sun, 2010-05-23 at 03:30 -0400, Mike Frysinger wrote:
> > From: Bernd Schmidt <bernds_cb1@t-online.de>
> > 
> > Currently, romfs XIP doesn't work in flash memory (the kernel crashes
> > with a null pointer dereference).  The problem is that the mtd physmap
> > driver isn't setting up a get_unmapped_area pointer for the mtd
> > partitions it creates.
> > 
> > Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
> > Signed-off-by: Mike Frysinger <vapier@gentoo.org>
> 
> Pushed both to my l2-mtd-2.6.git / dunno.

I'm confused by the second patch -- isn't this done in add_mtd_device()
already, according to the device type?

You're setting mtd_bdi_ro_mappable indiscriminately for all types of
devices. For flash devices, that can be an issue -- if you schedule a
userspace process while the kernel is writing to the flash, for example.

If you want to allow XIP of writable flash devices, there's more to it
than this.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation

  reply	other threads:[~2010-08-04  9:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-23  7:30 [PATCH 1/2] mtd: physmap: add physmap_unmapped_area() for no-mmu XIP Mike Frysinger
2010-05-23  7:30 ` [PATCH 2/2] mtd: physmap: allow maps to be read-only mapped Mike Frysinger
2010-06-12 14:26 ` [PATCH 1/2] mtd: physmap: add physmap_unmapped_area() for no-mmu XIP Artem Bityutskiy
2010-08-04  9:33   ` David Woodhouse [this message]
2010-08-07 23:26     ` [Uclinux-dist-devel] " Mike Frysinger
2010-08-08 11:33       ` David Woodhouse
2010-08-09  7:36         ` Mike Frysinger
2010-08-20  6:17   ` Artem Bityutskiy

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