From mboxrd@z Thu Jan 1 00:00:00 1970 From: AKASHI Takahiro Subject: Re: [PATCH v24 9/9] Documentation: dt: chosen properties for arm64 kdump Date: Mon, 22 Aug 2016 13:28:34 +0900 Message-ID: <20160822042832.GJ20080@linaro.org> References: <20160809015248.28414-2-takahiro.akashi@linaro.org> <20160809015747.28591-1-takahiro.akashi@linaro.org> <20160819132641.GA12709@rob-hp-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Return-path: Content-Disposition: inline In-Reply-To: <20160819132641.GA12709@rob-hp-laptop> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rob Herring Cc: 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, [Cc: Mark] On Fri, Aug 19, 2016 at 08:26:41AM -0500, Rob Herring wrote: > On Tue, Aug 09, 2016 at 10:57:47AM +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 | 50 ++++++++++++++++++++++++++++ > > 1 file changed, 50 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt > > index 6ae9d82..236188a 100644 > > --- a/Documentation/devicetree/bindings/chosen.txt > > +++ b/Documentation/devicetree/bindings/chosen.txt > > @@ -52,3 +52,53 @@ 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 (currently used on PowerPC and arm64) indicates > > +the base address and the size, respectively, of the reserved memory > > +range for crash dump kernel. > > +e.g. > > + > > +/ { > > + chosen { > > + linux,crashkernel-base = <0x9 0xf0000000>; > > + linux,crashkernel-size = <0x0 0x10000000>; > > + }; > > +}; > > + > > +linux,usable-memory-range > > +------------------------- > > + > > +This property (currently used only on arm64) holds the memory range, > > +the base address and the size, which can be used as system ram on > > +the *current* kernel. Note that, if this property is present, any memory > > +regions under "memory" nodes in DT blob or ones marked as "conventional > > +memory" in EFI memory map should be ignored. > > +e.g. > > + > > +/ { > > + chosen { > > + linux,usable-memory-range = <0x9 0xf0000000 0x0 0x10000000>; > > + }; > > +}; > > I've read the discussion on this. I think you should use the existing > linux,usable-memory property in the memory nodes. If UEFI systems don't > have memory nodes, then you can find an UEFI way to describe this. DT is > not the dumping ground for what doesn't fit in UEFI. How do x86 systems > work? Kdump for x86 passes the range of usable memory to crash dump kernel either via: (a) "memmap=nn@ss" command line parameter, or (b) faked BIOS e820 map (a sort of memory map table) (a) was rejected by Mark [1], and (b) is x86-specific. I believe that my approach is better because it works in the same way either on UEFI systems or DT-based systems. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/400122.html Thanks, -Takahiro AKASHI > Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html