From mboxrd@z Thu Jan 1 00:00:00 1970 From: nico@fluxnic.net (Nicolas Pitre) Date: Tue, 14 Sep 2010 14:46:06 -0400 (EDT) Subject: Maximum bootable kernel size in current ARM linux In-Reply-To: <4C8FB71C.8010208@endruntechnologies.com> References: <4C8DD588.7040009@endruntechnologies.com> <20100913100111.GA30787@n2100.arm.linux.org.uk> <4C8E7EFF.7020004@endruntechnologies.com> <4C8FB71C.8010208@endruntechnologies.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 14 Sep 2010, Bruce M. Penrod wrote: > > > Nicolas Pitre wrote: > > On Mon, 13 Sep 2010, Bruce M. Penrod wrote: > > > > > > > > Russell King - ARM Linux wrote: > > > > On Mon, Sep 13, 2010 at 12:40:56AM -0700, Bruce M. Penrod wrote: > > > > > This seems like a pretty straightforward question, but extensive web > > > > > searching hasn't shown a really clear, up-to-date answer. The most > > > > > recent info is circa 2004 and states that 4MB is the largest > > > > > uncompressed > > > > > ARM kernel that may be loaded. Not being an ARM assembly guru > > > > > (head.S > > > > > baffles me), I'd like to know if that is still true in 2010, and if > > > > > it > > > > > is, why? > > > > It is no longer true; the only limit now is the size of contiguous RAM > > > > to fit the kernel image into. > > > > > > > Interesting. I finally was able to get an uncompressed kernel a little > > > below > > > 4MB, and now it boots. I'm working with 2.6.35rc6 on an OpenRD Ultimate > > > (Marvell Kirkwood) with Slackware, doing native compiles. I'm wondering > > > if > > > there could be any problem with U-Boot for larger kernels than 4MB, but it > > > doesn't complain and says that it is copying the image. The symptom I had > > > with a much larger kernel (~15MB) is a total hang, not even "Uncompressing > > > linux". > > > > > > I'll add some innocuous stuff back in until I get above 4MB again and see > > > if > > > it breaks again. > > > > When it breaks, do you still see the "Uncompressing Linux... done, booting > > the kernel." message? > > > > > > Nicolas > > > > I think it depended upon how "too big" the kernel was. With one only slightly > larger than 4 MB, I did see "Uncompressing Linux...", but not "done, booting > the kernel." With a very large kernel (15MB), nothing printed at all. > > I have not retested since successfully booting one slightly smaller than 4096 > * 1024. When I do, I will post the results. Should happen today. OK. Also please provide the size of your arch/arm/boot/zImage as well as arch/arm/boot/Image. Also, at what address do you load your kernel in memory? Nicolas