From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH v2] ARM: new platform for Energy Micro's EFM32 Cortex-M3 SoCs Date: Sat, 28 Sep 2013 21:15:11 +0200 Message-ID: <20130928191511.GA2548@pengutronix.de> References: <1379447884-14025-1-git-send-email-u.kleine-koenig@pengutronix.de> <201309172245.25367.arnd@arndb.de> <20130926094251.GK16106@pengutronix.de> <201309272344.01386.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <201309272344.01386.arnd-r2nGTMty4D4@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: Olof Johansson , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Jonathan Austin List-Id: devicetree@vger.kernel.org Hi Arnd, On Fri, Sep 27, 2013 at 11:44:01PM +0200, Arnd Bergmann wrote: > On Thursday 26 September 2013, Uwe Kleine-K=F6nig wrote: > > I made that work now and can prepare a patch. I had to drop "depend= s on > > !ARCH_MULTIPLATFORM" from XIP_KERNEL. That's because my machine onl= y > > works with XIP_KERNEL as it only has 4 MiB of RAM. >=20 > Ok, cool. We might run into a few problems with 'make randconfig' and > 'make allyesconfig' when it becomes possible to enable XIP_KERNEL the= n. > IIRC, there is no fundamental reason to disallow XIP_KERNEL with > ARCH_MULTIPLATFORM, but I added the dependency because it causes > build errors in combination with other options. ah, OK. Do you have an idea to fix both? =20 > A few questions from my side, out of curiosity: >=20 > * Do you need any other patches (unrelated to EFM32) to run NOMMU on = a > recent kernel? When I last tried, I could not get any NOMMU build to = work > at all. no, there isn't much needed on top of current mainline. My current wip = is at git://git.pengutronix.de/git/ukl/linux.git efm32 I don't even rely on all the HACK-patches that are included there. (The multi-arch stuff isn't there yet.) =20 > * Do you think 4MB is now a strict lower bound for running a modern > kernel? It would be a good data point if we could show that any targe= t > with less than that is by definition broken and could get removed > from the kernel. What is the size of your kernel and user space? $ objdump -p vmlinux vmlinux: file format elf32-littlearm Program Header: LOAD off 0x00000000 vaddr 0x88020000 paddr 0x88020000 align 2**1= 5 filesz 0x00000094 memsz 0x0000a9f4 flags rw- LOAD off 0x00008000 vaddr 0x8c000000 paddr 0x8c000000 align 2**1= 5 filesz 0x001679b0 memsz 0x001679b0 flags rwx LOAD off 0x00170000 vaddr 0x88008000 paddr 0x8c1679b0 align 2**1= 5 filesz 0x00018d2c memsz 0x00018d2c flags rw- private flags =3D 5000002: [Version5 EABI] [has entry point] my rootfs (busybox, no init) is 153600 bytes big. After booting I get: / # free total used free shared buffers Mem: 3892 1428 2464 0 0 -/+ buffers: 1428 2464 but it doesn't run anything but a busybox shell ATM. Assuming the next smaller configuration is 2 MiB of RAM I'd say that machine can maybe boot, but cannot do anything sensible after that. > * What user space are you running? Anything that's easy to build > for testing? Should that run with a mach-virt kernel built for > ARMv7-A NOMMU? There is a BSP publically available at http://git-public.pengutronix.de/?p=3DOSELAS.BSP-EnergyMicro-Gecko.git= ;a=3Dsummary which also includes a README file. For troubleshooting /join #efm32 on freenode. =20 > * An ARMv7-M kernel cannot run on either ARMv4/v5 nor ARMv6/v7-A, rig= ht? The entry convention is different (ARMv7-M doesn't support the ARM instruction set but you need to jump into the kernel in ARM mode for v4-v7). Other that that I don't know if there is a problem. Maybe Jonathan can say anything here? Or alternatively if you want an efm32 devboard, just tell me. > Do you prevent building such a kernel in Kconfig? I'm sure my Kconfig magic isn't waterproof. It took me a few tries to expand the multiarch architecture selection to make v7-m selectable at all. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html