linux-kernel - Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager

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]

Message-Id: <20100713173028M.fujita.tomonori@lab.ntt.co.jp>
Date:	Tue, 13 Jul 2010 17:30:43 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	alan@...rguk.ukuu.org.uk
Cc:	fujita.tomonori@....ntt.co.jp, zpfeffer@...eaurora.org,
	joro@...tes.org, dwalker@...eaurora.org, andi@...stfloor.org,
	randy.dunlap@...cle.com, mel@....ul.ie, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager

On Tue, 13 Jul 2010 09:20:12 +0100
Alan Cox <alan@...rguk.ukuu.org.uk> wrote:

> > Why video4linux can't use the DMA API? Doing DMA with vmalloc'ed
> > buffers is a thing that we should avoid (there are some exceptions
> > like xfs though).
> 
> Vmalloc is about the only API for creating virtually linear memory areas.
> The video stuff really needs that to avoid lots of horrible special cases
> when doing buffer processing and the like.
> 
> Pretty much each driver using it has a pair of functions 'rvmalloc' and
> 'rvfree' so given a proper "vmalloc_for_dma()" type interface can easily
> be switched

We already have helper functions for DMA with vmap pages,
flush_kernel_vmap_range and invalidate_kernel_vmap_range.

I think that the current DMA API with the above helper functions
should work well drivers that want virtually linear large memory areas
(such as xfs).
--
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/