From mboxrd@z Thu Jan 1 00:00:00 1970 From: AKASHI Takahiro Subject: Re: [PATCH v23 9/9] Documentation: dt: chosen properties for arm64 kdump Date: Thu, 4 Aug 2016 14:10:11 +0900 Message-ID: <20160804051010.GK7995@linaro.org> References: <20160726075659.2290-1-takahiro.akashi@linaro.org> <20160726080206.2441-1-takahiro.akashi@linaro.org> <20160727150933.GA25732@rob-hp-laptop> <20160728075511.GA7995@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20160728075511.GA7995-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Rob Herring , catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, james.morse-5wv7dgnIgG8@public.gmane.org, geoff-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, bauerman-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Rob, On Thu, Jul 28, 2016 at 04:55:11PM +0900, AKASHI Takahiro wrote: > Rob, > > On Wed, Jul 27, 2016 at 10:09:33AM -0500, Rob Herring wrote: > > On Tue, Jul 26, 2016 at 05:02:06PM +0900, AKASHI Takahiro wrote: > > > From: James Morse > > > > > > Add documentation for > > > linux,crashkernel-base and crashkernel-size, > > > linux,usable-memory-range, and > > > linux,elfcorehdr > > > used by arm64 kexec/kdump to decribe the kdump reserved area, and > > > the elfcorehdr's location within it. > > > > > > Signed-off-by: James Morse > > > [takahiro.akashi-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org: > > > renamed "usable-memory" to "usable-memory-range", > > > added "linux,crashkernel-base" and "-size" ] > > > Signed-off-by: AKASHI Takahiro > > > --- > > > Documentation/devicetree/bindings/chosen.txt | 45 ++++++++++++++++++++++++++++ > > > 1 file changed, 45 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt > > > index 6ae9d82..d7a3a86 100644 > > > --- a/Documentation/devicetree/bindings/chosen.txt > > > +++ b/Documentation/devicetree/bindings/chosen.txt > > > @@ -52,3 +52,48 @@ This property is set (currently only on PowerPC, and only needed on > > > book3e) by some versions of kexec-tools to tell the new kernel that it > > > is being booted by kexec, as the booting environment may differ (e.g. > > > a different secondary CPU release mechanism) > > > + > > > +linux,crashkernel-base > > > +linux,crashkernel-size > > > +---------------------- > > > +These properties are set (on PowerPC and arm64) during kdump to tell > > > +use-space tools, like kexec-tools, the base address of the crash-dump > > > > s/use/user/ > > > > Ideally, userspace should not care whether this comes from DT, kernel > > command-line or somewhere else and should be exposed in some source > > independent way. However, that's not really the problem for the binding. > > Yeah, I will remove "user-space"-related description as Mark also > commented before. > > > > +kernel's reserved area of memory and the size. e.g. > > > + > > > +/ { > > > + chosen { > > > + linux,crashkernel-base = <0x9 0xf0000000>; > > > + linux,crashkernel-size = <0x0 0x10000000>; > > > + }; > > > +}; > > > + > > > +linux,usable-memory-range > > > +------------------------- > > > + > > > +This property is set (currently only on arm64) during kdump to tell > > > +the crash-dump kernel the base address of its reserved area of memory, > > > +and the size. e.g. > > > + > > > +/ { > > > + chosen { > > > + linux,usable-memory-range = <0x9 0xf0000000 0x0 0x10000000>; > > > > This is the same range as linux,crashkernel-*, but used by the 2nd > > kernel? Why not just update the memory node or use command line mem= > > parameter? > > Please see: > http://lists.infradead.org/pipermail/linux-arm-kernel/2016-July/443225.html > > There was also a discussion that simply appending "mem=", or more generally > any parameter, to a command line might break some assumption of order of > parameters in the future. > So adding a DT property would be a better way. Do you have any other comments about those properties? -Takahiro AKASHI > Thanks, > -Takahiro AKASHI > > > Why has PPC not need this and ARM does? > > > > > + }; > > > +}; > > > + > > > +Please note that, if this property is present, any memory regions under > > > +"memory" nodes will be ignored. > > > + > > > +linux,elfcorehdr > > > +---------------- > > > + > > > +This property is set (currently only on arm64) during kdump to tell > > > +the crash-dump kernel the address and size of the elfcorehdr that describes > > > +the old kernel's memory as an elf file. This memory must reside within > > > +the area described by 'linux,usable-memory-range'. e.g. > > > + > > > +/ { > > > + chosen { > > > + linux,usable-memory = <0x9 0xf0000000 0x0 0x10000000>; > > > + linux,elfcorehdr = <0x9 0xfffff000 0x0 0x800>; > > > + }; > > > +}; > > > -- > > > 2.9.0 > > >