From mboxrd@z Thu Jan 1 00:00:00 1970 From: cyril@ti.com (Cyril Chemparathy) Date: Mon, 24 Sep 2012 16:59:50 -0400 Subject: [PATCH v3 RESEND 05/17] ARM: LPAE: support 64-bit virt_to_phys patching In-Reply-To: References: <1348242975-19184-1-git-send-email-cyril@ti.com> <1348242975-19184-6-git-send-email-cyril@ti.com> <20120924151305.GA14198@arm.com> Message-ID: <5060C9C6.8080900@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 9/24/2012 11:56 AM, Nicolas Pitre wrote: > On Mon, 24 Sep 2012, Catalin Marinas wrote: > >> On Fri, Sep 21, 2012 at 04:56:03PM +0100, Cyril Chemparathy wrote: >>> This patch adds support for 64-bit physical addresses in virt_to_phys() >>> patching. This does not do real 64-bit add/sub, but instead patches in the >>> upper 32-bits of the phys_offset directly into the output of virt_to_phys. >> >> So this assumes that for the kernel linear mapping, all the physical >> addresses have the same upper 32-bit. That's a good optimisation but I >> haven't seen this check when calculating lowmem in sanity_check_meminfo. >> Someone may build platform with memory starting at 3GB and going across >> the 4GB limit. > > Good point. We better get an early warning if that happens. > Thanks. I'm thinking of splitting the bank at the 32-bit boundary in such an event, assuming that the remaining memory should be usable as highmem. -- Thanks - Cyril