From: Andy Lutomirski <luto@amacapital.net>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 17/25] drm: rip out drm_core_has_MTRR checks
Date: Fri, 9 Aug 2013 11:48:27 -0700 [thread overview]
Message-ID: <CALCETrWRJkz7teJO4J-RyHPX37WjjNyhK6AQC2B4kW3osETD3A@mail.gmail.com> (raw)
In-Reply-To: <CAKMK7uF4arOUXgeC9PJR9R-8x-x1TK9wdFr4qcaJ399MSA-pog@mail.gmail.com>
On Fri, Aug 9, 2013 at 11:47 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> On Fri, Aug 9, 2013 at 8:39 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>> On Fri, Aug 9, 2013 at 11:36 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>>> On Fri, Aug 9, 2013 at 8:12 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>>> On Thu, Aug 8, 2013 at 6:41 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>>>>> The new arch_phys_wc_add/del functions do the right thing both with
>>>>> and without MTRR support in the kernel. So we can drop these
>>>>> additional checks.
>>>>
>>>> If any of the new arch_phys_wc_add calls are reachable and if the
>>>> driver calls arch_phys_wc_add itself, then the lack of refcounting on
>>>> non-PAT systems may cause a problem. (I don't understand the drm
>>>> stuff well enough to know whether that can actually happen.)
>>>
>>> This is only about compile-time options really. Somehow drm had the
>>> idea to use these check functions instead of #ifdef plus dummy static
>>> inline noop functions. David Herrmann just did the same patch for the
>>> agp stuff. So refcounting is of no concern here.
>>
>> I feel like I'm missing something obvious here. On nouveau, prior to
>> this patch, the drm maps code would not touch mtrrs. Now it will.
>> Nouveau already calls arch_phys_wc_add, so if that maps code is
>> reached on the same resource, then there could be refcounting issues.
>
> Oh that kind of confusion. The maps code here is for old userspace
> drivers, I have some patches in the queue that will disable it
> properly for kms drivers. So it should never happen that both the kms
> driver and the maps code in the drm core set up a mtrr mapping. And if
> it happens someone is doing something really nasty, and that hole will
> soon be plugged.
In that case, I'm convinced. In case you care:
Acked-by: Andy Lutomirski <luto@amacapital.net>
--Andy
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
--
Andy Lutomirski
AMA Capital Management, LLC
next prev parent reply other threads:[~2013-08-09 18:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-08 13:41 [PATCH 00/25] drm cruft removal Daniel Vetter
2013-08-08 13:41 ` [PATCH 01/25] drm/omap: kill firstopen callback Daniel Vetter
2013-08-08 14:04 ` Rob Clark
2013-08-08 13:41 ` [PATCH 02/25] drm/radeon: kill firstopen callback for kms driver Daniel Vetter
2013-08-08 13:41 ` [PATCH 03/25] drm/imx: kill firstopen callback Daniel Vetter
2013-08-12 22:23 ` Greg Kroah-Hartman
2013-08-08 13:41 ` [PATCH 04/25] drm/vmwgfx: remove ->firstopen callback Daniel Vetter
2013-08-08 13:41 ` [PATCH 05/25] drm: don't call ->firstopen for KMS drivers Daniel Vetter
2013-08-08 13:41 ` [PATCH 06/25] drm: kill dev->driver->set_version Daniel Vetter
2013-08-08 14:10 ` Rob Clark
2013-08-08 13:41 ` [PATCH 07/25] drm: hide legacy sg cleanup better from common code Daniel Vetter
2013-08-08 13:41 ` [PATCH 08/25] drm: disallow legacy sg ioctls for modesetting drivers Daniel Vetter
2013-08-08 13:41 ` [PATCH 09/25] drm: mark dma setup/teardown as legacy systems Daniel Vetter
2013-08-08 13:41 ` [PATCH 10/25] drm: disallow legacy dma ioctls for modesetting drivers Daniel Vetter
2013-08-08 13:41 ` [PATCH 11/25] drm: mark context support as a legacy subsystem Daniel Vetter
2013-08-08 13:41 ` [PATCH 12/25] drm/vmwgfx: remove redundant clearing of driver->dma_quiescent Daniel Vetter
2013-08-08 13:41 ` [PATCH 13/25] drm: remove FASYNC support Daniel Vetter
2013-08-13 19:26 ` David Herrmann
2013-08-08 13:41 ` [PATCH 14/25] drm: rip out DRIVER_FB_DMA and related code Daniel Vetter
2013-08-08 13:41 ` [PATCH 15/25] drm: rip out a few unused DRIVER flags Daniel Vetter
2013-08-08 13:41 ` [PATCH 16/25] drm: remove a bunch of unused #defines from drmP.h Daniel Vetter
2013-08-08 13:41 ` [PATCH 17/25] drm: rip out drm_core_has_MTRR checks Daniel Vetter
2013-08-09 18:12 ` Andy Lutomirski
2013-08-09 18:36 ` Daniel Vetter
2013-08-09 18:39 ` Andy Lutomirski
2013-08-09 18:47 ` Daniel Vetter
2013-08-09 18:48 ` Andy Lutomirski [this message]
2013-08-15 12:44 ` David Herrmann
2013-08-08 13:41 ` [PATCH 18/25] drm/docs: rip out removed driver flags documentation Daniel Vetter
2013-08-08 13:41 ` [PATCH 19/25] drm: remove the dma_ioctl special-case Daniel Vetter
2013-08-13 18:05 ` David Herrmann
2013-08-08 13:41 ` [PATCH 20/25] drm/memory: don't export agp helpers Daniel Vetter
2013-08-08 13:41 ` [PATCH 21/25] drm: hollow-out GET_CLIENT ioctl Daniel Vetter
2013-08-08 13:41 ` [PATCH 22/25] drm: no-op out GET_STATS ioctl Daniel Vetter
2013-08-08 15:55 ` Eric Anholt
2013-08-09 9:05 ` Daniel Vetter
2013-08-08 13:41 ` [PATCH 23/25] drm: fix locking in gem debugfs/procfs file Daniel Vetter
2013-08-08 13:41 ` [PATCH 24/25] drm: remove procfs code, take 2 Daniel Vetter
2013-08-08 13:41 ` [PATCH 25/25] drm: move dev data clearing from drm_setup to lastclose Daniel Vetter
2013-08-13 18:12 ` David Herrmann
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