Re: [PATCH] ARM: allow, but warn, when issuing ioremap() on RAM
[Posted October 12, 2010 by corbet]
| From: |
| Andrew Morton <akpm-AT-linux-foundation.org> |
| To: |
| Russell King - ARM Linux <linux-AT-arm.linux.org.uk> |
| Subject: |
| Re: [PATCH] ARM: allow, but warn, when issuing ioremap() on RAM |
| Date: |
| Fri, 8 Oct 2010 12:58:03 -0700 |
| Message-ID: |
| <20101008125803.e5bc7306.akpm@linux-foundation.org> |
| Cc: |
| Felipe Contreras <felipe.contreras-AT-gmail.com>,
linux-main <linux-kernel-AT-vger.kernel.org>,
linux-arm <linux-arm-kernel-AT-lists.infradead.org>,
Arnd Hannemann <arnd-AT-arndnet.de>,
Han Jonghun <jonghun79.han-AT-gmail.com>,
Uwe =?ISO-8859-1?Q?Kleine-K=F6nig?=
<u.kleine-koenig-AT-pengutronix.de>, Hemant Pedanekar <hemantp-AT-ti.com> |
| Archive‑link: | |
Article |
On Thu, 7 Oct 2010 20:22:45 +0100
Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> On Thu, Oct 07, 2010 at 12:44:22PM +0300, Felipe Contreras wrote:
> > Many drivers are broken, and there's no alternative in sight. Such a big
> > change should stay as a warning for now, and only later should it
> > actually fail.
> >
> > The drivers are not doing something correct, we get it, but for now it's
> > better to allow them to work (they do 99% of the time anyway) rather
> > than to force everyone to revert this patch in their internal trees
> > until there's a solution. A slightly broken functionality is better than
> > no functionality at all.
> >
> > A warning lets people know that what they are doing is not right, and
> > they should fix it.
>
> So what are _you_ going to do to fix these drivers? Continue reverting
> this patch? Or are you just going to ignore the issue entirely?
>
> Unless people can come up with a plan to fix their drivers using ioremap
> on system RAM thereby violating the architecture specification, I'm
> _not_ going to apply this patch.
We *do* have a plan: as of 2.6.36, the kernel will emit a WARN_ON trace
when a driver does this. Offending code will be discovered, developers
will get bug reports from worried users, etc. This is usually pretty
effective.