From: Eric Anholt <eric@anholt.net>
To: Ben Widawsky <ben@bwidawsk.net>, intel-gfx@lists.freedesktop.org
Subject: Re: No more read/write ioctls
Date: Fri, 08 Apr 2011 07:10:14 -1000 [thread overview]
Message-ID: <87fwpsfz49.fsf@pollan.anholt.net> (raw)
In-Reply-To: <20110406213826.GA32472@snipes.kumite>
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On Wed, 6 Apr 2011 14:38:27 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Fri, Apr 01, 2011 at 04:54:47PM -0700, Ben Widawsky wrote:
>
> > So if this isn't okay by everyone, let's get down to the minimum number
> > of changes required to get this accepted so I can move on to the tools,
> > and then get back to the debug stuff.
> >
>
> Some discussion on IRC has led to a new proposal (well 2 new proposals,
> but the first one wasn't viable).
>
> The interface will instead of using ioctls use debugfs. The debugfs file
> will control force wake. There will be a refcount mechanism for number
> of users of the registers in the relevant power-well, and upon opening a
> specific file in debugfs (we could have one per power-well if needed),
> the refcount will get incremented, and decremented at close.
>
> In other words, for userspace to read/write registers:
> fd = open(/sys/kernel/debug/dri...)
> normal read write mechanism
> close(fd)
>
> There are two side effects which everyone on IRC seems fine with:
> * root-only read access (the ioctl read was promiscuous)
> * access is only available when debugfs is mounted
>
> As a result, you should ignore both the gpu-tools patches, as well as
> these kernel patches.
I thought previously we had issues with debugfs nodes which could wedge
the system (out of range mmio reads)?
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next prev parent reply other threads:[~2011-04-08 17:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 1:31 [PATCH] drm/i915: read/write IOCTLs Ben Widawsky
2011-04-01 1:39 ` [PATCH v2] " Ben Widawsky
2011-04-01 23:54 ` Read/Write IOCTL compromise Ben Widawsky
2011-04-06 21:38 ` No more read/write ioctls Ben Widawsky
2011-04-08 17:10 ` Eric Anholt [this message]
2011-04-08 17:29 ` Chris Wilson
2011-04-01 23:54 ` [PATCH v3 1/2] drm/i915: read/write ioctls for userspace Ben Widawsky
2011-04-04 17:14 ` Chris Wilson
2011-04-05 1:30 ` Read/Write ioctls Ben Widawsky
2011-04-05 1:30 ` [PATCH v4] drm/i915: read/write ioctls for userspace Ben Widawsky
2011-04-01 23:54 ` [PATCH v3 2/2] drm/i915: debugfs for register write taint Ben Widawsky
2011-04-01 6:36 ` [PATCH] drm/i915: read/write IOCTLs Chris Wilson
2011-04-01 7:06 ` Ben Widawsky
2011-04-01 7:32 ` Chris Wilson
2011-04-01 18:51 ` Eric Anholt
2011-04-02 6:46 ` Chris Wilson
2011-04-02 15:16 ` Ben Widawsky
2011-04-04 1:35 ` Ben Widawsky
2011-04-04 7:36 ` Chris Wilson
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