linux-kernel - Re: [Linaro-acpi] [PATCH v5 18/18] Documentation: ACPI for ARM64

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20150109151342.GE24408@e104818-lin.cambridge.arm.com>
Date:	Fri, 9 Jan 2015 15:13:43 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Rob Herring <robh@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Robert Richter <rric@...nel.org>,
	Jason Cooper <jason@...edaemon.net>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	Marc Zyngier <Marc.Zyngier@....com>,
	"jcm@...hat.com" <jcm@...hat.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Robert Moore <robert.moore@...el.com>,
	Will Deacon <Will.Deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Mark Brown <broonie@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Lv Zheng <lv.zheng@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Olof Johansson <olof@...om.net>
Subject: Re: [Linaro-acpi] [PATCH v5 18/18] Documentation: ACPI for ARM64

On Fri, Jan 09, 2015 at 10:55:51AM +0000, Arnd Bergmann wrote:
> On Friday 09 January 2015 10:33:07 Catalin Marinas wrote:
> > On Wed, Jan 07, 2015 at 07:48:48PM +0000, Arnd Bergmann wrote:
> 
> > > In other cases that's actually a good thing. One such example is the
> > > "Principles of ARM Memory Maps" document that tells hardware implementers
> > > to do a rather complex mapping "To support 36-bit x86 PAE compatible operating
> > > systems, such as Linux." but makes life much harder in the process than
> > > any of the random mappings we have seen in the wild.
> > 
> > Unfortunately, with any significant amount of RAM (say 16GB), this
> > document becomes pretty useless. It basically forces you to have a very
> > sparse physical address map from 0 to over 40-bit. I wouldn't apply the
> > ARM memory maps doc to server systems.
> 
> Are you sure? I was under the impression that this document was targetted
> specifically at servers.

Ah, sorry for the confusion, I haven't read the latest (apparently from
2012) update which covers 44 and 48-bit memory maps.

The only downside is that for more than 32GB of RAM (up to 512GB) it
requires a 40-bit memory map. Given the sparseness, we can't use
3-levels of page table with 4KB pages which can only cover 39-bit.
Anyway, not a major issue.

-- 
Catalin
--
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/