From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Fri, 17 Sep 2010 11:09:53 +0100 Subject: Maximum bootable kernel size in current ARM linux In-Reply-To: References: <4C8DD588.7040009@endruntechnologies.com> <201009131043.48688.marek.vasut@gmail.com> <20100913101039.GC2614@kw.sim.vm.gnt> <000001cb5409$4726e000$4b4d010a@Emea.Arm.com> <1284468849.933.2.camel@e102109-lin.cambridge.arm.com> <1284657411.32513.3.camel@e102109-lin.cambridge.arm.com> Message-ID: <1284718193.22217.11.camel@e102109-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2010-09-16 at 13:58 -0400, Nicolas Pitre wrote: > On Thu, 16 Sep 2010, Catalin Marinas wrote: > > > On Tue, 2010-09-14 at 13:37 -0400, Nicolas Pitre wrote: > > > On Tue, 14 Sep 2010, Catalin Marinas wrote: > > > > > > > I think the Thumb-2 branch goes up to 16MB range. The Thumb-1 may be > > > > smaller but we don't support this in the kernel. That's why Thumb-2 > > > > modules are within 8MB below PAGE_OFFSET. But this leaves us with > > > > maximum 8MB of kernel size. > > > > > > Hmmm. Would be worth moving the pkmap area below modules then. > > > > So currently the pkmap area is at PAGE_OFFSET - 2MB. On a Thumb-2 kernel > > with highmem enabled we would have 6MB available to modules. Is this big > > enough? If not, we could move the pkmap area. > > It is probably enough. But it is just not optimal. If the area between > TASK_SIZE and PAGE_OFFSET-8M is unused, then it would make sense to move > the pkmap area there instead. I agree. -- Catalin