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From: Alyssa Rosenzweig <alyssa@collabora.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Steven Price <steven.price@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/panfrost: Add PANFROST_BO_NO{READ,WRITE} flags
Date: Thu, 30 Sep 2021 18:12:11 -0400	[thread overview]
Message-ID: <YVY2O48ckub2fc5W@maud> (raw)
In-Reply-To: <20210930214030.19f63eac@collabora.com>

> > > +	/* Executable implies readable */
> > > +	if ((args->flags & PANFROST_BO_NOREAD) &&
> > > +	    !(args->flags & PANFROST_BO_NOEXEC))
> > > +		return -EINVAL;  
> > 
> > Generally, executable also implies not-writeable. Should we check that?
> 
> We were allowing it until now, so doing that would break the backward
> compat, unfortunately.

Not a problem if you only enforce this starting with the appropriate
UABI version, but...

> Steve also mentioned that the DDK might use shaders modifying other
> shaders here [1]

What? I believe it, but what?

For the case of pilot shaders, that shouldn't require self-modifying
code. As I understand, the DDK binds the push uniform (FAU / RMU) buffer
as global shader memory (SSBO) and uses regular STORE instructions on
it. That requires writability on that BO but that should be fine.

  reply	other threads:[~2021-09-30 22:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-30 18:47 [PATCH] drm/panfrost: Add PANFROST_BO_NO{READ,WRITE} flags Boris Brezillon
2021-09-30 19:13 ` Alyssa Rosenzweig
2021-09-30 19:40   ` Boris Brezillon
2021-09-30 22:12     ` Alyssa Rosenzweig [this message]
2021-10-01  6:47       ` Boris Brezillon
2021-10-01 11:48         ` Alyssa Rosenzweig
2021-10-01 12:09       ` Steven Price
2021-09-30 19:44 ` Boris Brezillon
2021-10-01  7:06   ` Boris Brezillon

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