From mboxrd@z Thu Jan 1 00:00:00 1970 From: geoff@infradead.org (Geoff Levand) Date: Thu, 07 Aug 2014 10:09:39 -0700 Subject: Kexec on arm64 In-Reply-To: <20140807095919.GC9984@leverpostej> References: <20140728153812.GA2576@leverpostej> <1406592548.28348.49.camel@smoke> <20140729133557.GQ2576@leverpostej> <1406668741.28348.75.camel@smoke> <20140804113528.GC3197@leverpostej> <1407372003.8971.85.camel@smoke> <20140807095919.GC9984@leverpostej> Message-ID: <1407431379.8971.91.camel@smoke> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2014-08-07 at 10:59 +0100, Mark Rutland wrote: > On Thu, Aug 07, 2014 at 01:40:03AM +0100, Geoff Levand wrote: > > > > I haven't looked into it yet, but booting.txt says that the dtb must be > > 'within the first 512 megabytes from the start of the kernel image'. If > > this restriction still holds we can't just put the dtb at > > text_offset + image_size. > > Isn't that only a problem if text_offset + image_size is huge (510MB+)? Yes, a limit I don't think we need to be too concerned about at present. > The wording in booting.txt doesn't sound quite right. As I understand > it, the 512MB restriction is because of the way we map the dtb in the > swapper page tables. > > So a better wording would be "the kernel and DTB must be placed in the > same naturally-aligned 512MB region of memory". > > It should be possible to get rid of the restrictions on the placement of > the image and DTB, but this requires reworking the VA layout (using a > kernel text mapping separate from the linear map as with x86_64, and > similarly having a separate DTB mapping), and unfortunately I haven't > had the time to do that. Or maybe just relocate the dtb at startup to within range. -Geoff