From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian.Campbell@citrix.com (Ian Campbell) Date: Tue, 30 Jul 2013 15:30:51 +0100 Subject: [PATCH] arm: update advice on kernel and FDT load address. In-Reply-To: <20130730140451.GQ24642@n2100.arm.linux.org.uk> References: <1375102578-5869-1-git-send-email-ian.campbell@citrix.com> <20130729135000.GK32383@mudshark.cambridge.arm.com> <1375106635.12741.8.camel@kazak.uk.xensource.com> <1375192570.32691.27.camel@kazak.uk.xensource.com> <20130730140451.GQ24642@n2100.arm.linux.org.uk> Message-ID: <1375194651.32691.52.camel@kazak.uk.xensource.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 2013-07-30 at 15:04 +0100, Russell King - ARM Linux wrote: > On Tue, Jul 30, 2013 at 02:56:10PM +0100, Ian Campbell wrote: > > Actually I've just noticed that the existing text in > > Documentation/arm/Booting only talks about zImage and 32KiB, so perhaps > > not worrying about non-zImage is acceptable? > > Straight binary kernels have tighter requirements, because they're _not_ > entirely position independent. Firstly, with dynamic physical offset, > they calculate that based on their position in physical space when > they're first called. > > So, with a PAGE_OFFSET of 0xc0000000 and a link address of 0xc0008000, > a binary kernel image better be placed at 0xXXXX8000, and it _will_ > assume that RAM starts 32KiB below itself. And yes, the 32KiB offset > applies as the kernel uses TEXTADDR-16KiB to store the initial page > tables. OK, so in the non-zImage case 32KiB is a Requirement and not just a recommendation. I'll update things to that affect. This is turning out to be more complicated to write down than I imagined! Ian.