linux-kernel - Re: dma-buf/sync_file: de-stage sync

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Date:	Wed, 25 May 2016 22:42:09 -0400
From:	Dave Jones <davej@...emonkey.org.uk>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: dma-buf/sync_file: de-stage sync_file

On Sat, May 21, 2016 at 05:31:53AM +0000, Linux Kernel wrote:
 
 >     dma-buf/sync_file: de-stage sync_file
 >     
 >     sync_file is useful to connect one or more fences to the file. The file is
 >     used by userspace to track fences between drivers that share DMA bufs.
 >     
 >     Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
 >     Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
 >     Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

 ...
 
 > +config SYNC_FILE
 > +	bool "sync_file support for fences"
 > +	default n
 > +	select ANON_INODES
 > +	select DMA_SHARED_BUFFER
 > +	---help---
 > +	  This option enables the fence framework synchronization to export
 > +	  sync_files to userspace that can represent one or more fences.

For such a generic sounding CONFIG_ item, this is one of the more obtuse descriptions
in a kconfig we've had in a while, and the commit message doesn't give any more
clues as to why anyone might want to enable this.

I'm guessing this is some graphics thing given that Daniel reviewed it.
>From skimming the other commits, it seems to be some Android thing ?
Are there depends missing perhaps that might make this more obvious ?

Could you elaborate in the help text why someone might want to enable this ?
As is, it's just a bunch of words with no context for anyone who isn't
close to whatever domain this came from.

	Dave