linux-kernel - Re: [Q] block / zynq: DMA bouncing

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: <20140127175231.GU15937@n2100.arm.linux.org.uk>
Date:	Mon, 27 Jan 2014 17:52:31 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Michal Simek <monstr@...str.eu>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [Q] block / zynq: DMA bouncing

On Mon, Jan 27, 2014 at 06:45:50PM +0100, Michal Simek wrote:
> Why 0x4000? IRC Linux for ARM is using space for any purpose.
> Russell knows this much better than I.

Probably because as the kernel is loaded at 0x8000, it will place the
swapper page table at 0x4000, thus covering from 0x4000 upwards.

Thus, the majority of your un-DMA-able memory will be kernel text or
swapper page tables.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".
--
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/