linux-kernel - Re: Vramfs: filesystem driver to utilize extra RAM on VGA devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 29 Jan 2009 09:38:39 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jonathan Campbell <jon@...dgrounds.com>
CC:	"Peter W. Morreale" <pmorreale@...ell.com>,
	devel@...verdev.osuosl.org,
	Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: Vramfs: filesystem driver to utilize extra RAM on VGA devices

Jonathan Campbell wrote:
> Every VGA device connected to the PCI bus has resources that are known
> to the Linux kernel. One of the memory resources is the video RAM
> (always the largest prefetchable resource listed), with the base and
> length known to the PCI subsystem. So, all vramfs needs on mount is the
> PCI device, and the mountpoint, and it can dole it out to userspace.
> Reading and writing is handled with ioremap(). mmap() is handled by
> directly mmaping() that VRAM into user-space (just like /dev/fb0). Files
> are recorded in system memory as a list of entities with a starting
> block and length, so no fragmentation is possible.
> 
> No communication with the GPU is needed to do this, it's possible to use
> VRAM this way even on devices that nobody in the system knows how to
> talk to.

There still seems to be quite a bit of overlap between this and the MTD
subsystem...

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/