From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Wed, 11 Mar 2015 10:04:21 +0000 Subject: [PATCH 3/5] arm64: Documentation: clarify Image placement in physical RAM In-Reply-To: <1425380630-3684-4-git-send-email-ard.biesheuvel@linaro.org> References: <1425380630-3684-1-git-send-email-ard.biesheuvel@linaro.org> <1425380630-3684-4-git-send-email-ard.biesheuvel@linaro.org> Message-ID: <20150311100421.GA4114@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Mar 03, 2015 at 11:03:48AM +0000, Ard Biesheuvel wrote: > The early init code maps the kernel image using statically > allocated page tables. This means that we can only allow > Image to be placed such that we can map its entire static > footprint using a single table entry at all but the lowest > level. So update the documentation to reflect that the Image > should not cross a 512 MB boundary, which ensures the above > on both 4k and 64k pages kernels. > > Signed-off-by: Ard Biesheuvel > --- > Documentation/arm64/booting.txt | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt > index bdc35fc97ac8..49f17b1632f1 100644 > --- a/Documentation/arm64/booting.txt > +++ b/Documentation/arm64/booting.txt > @@ -112,8 +112,9 @@ The Image must be placed text_offset bytes from a 2MB aligned base > address near the start of usable system RAM and called there. Memory > below that base address is currently unusable by Linux, and therefore it > is strongly recommended that this location is the start of system RAM. > -At least image_size bytes from the start of the image must be free for > -use by the kernel. > +The physical memory region consisting of image_size bytes counting from > +the start of the image must be free for use by the kernel, and must not > +cross a 512 MB physical alignment boundary. This is correct. I had a go at rewording this so as to move all the address restrictions together, but I couldn't make it any clearer than the wording above. So FWIW: Reviewed-by: Mark Rutland Mark.