From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 17 Nov 2014 21:41:02 +0100 (CET) Received: from mout.kundenserver.de ([212.227.126.131]:61525 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27013859AbaKQUlAq7eNi (ORCPT ); Mon, 17 Nov 2014 21:41:00 +0100 Received: from wuerfel.localnet (HSI-KBW-149-172-15-242.hsi13.kabel-badenwuerttemberg.de [149.172.15.242]) by mrelayeu.kundenserver.de (node=mreue005) with ESMTP (Nemesis) id 0MLkAx-1XqC7V2Xhb-000weI; Mon, 17 Nov 2014 21:40:50 +0100 From: Arnd Bergmann To: Kevin Cernekee Cc: Ralf Baechle , Florian Fainelli , Jon Fraser , Dmitry Torokhov , Thomas Gleixner , Jason Cooper , Linux MIPS Mailing List , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jonas Gorski Subject: Re: [PATCH V2 22/22] MIPS: Add multiplatform BMIPS target Date: Mon, 17 Nov 2014 21:40:50 +0100 Message-ID: <3357597.nYlNZ6O0nJ@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1416097066-20452-1-git-send-email-cernekee@gmail.com> <2911624.UJRs5QOPN5@wuerfel> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:SmsAtINU2qaB3wgfto3BZGVZ0mWGoaHI3kXMX3aO7xT cFTdHLZcxcgTOC7uMimIWkY5CQPOjPWYs7wLDJWmc/07jX+OzL AuTfUTwci+vfIAmyP4rexTejvePxGjkNx/UJx5KmYJ2Lk0ioBu WaFI/Q8pwcBF5IrUN0V0/JxafXIAMpUJxYlSj2Y+hNF24NrRK3 i2ykAA6TE+rgAs1S38AcOIaxC2IvLjm06h1OudNf2WoU9V+vg7 AWTYujCNVm/TkbS1CVn6jsUeCcN6AjZjfG8JdlkXgbL0QKYD2Y 3bhugQpyvCJhFTqzjfEIZSNjYRstQr1fldzi32kTCHO1t1UV+4 HOLkUBO6pakJcKhvAraM= X-UI-Out-Filterresults: notjunk:1; Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 44248 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: arnd@arndb.de Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Monday 17 November 2014 11:39:02 Kevin Cernekee wrote: > On Mon, Nov 17, 2014 at 10:46 AM, Arnd Bergmann wrote: > > On Monday 17 November 2014 09:01:02 Kevin Cernekee wrote: > >> > If you wanted to do that however, starting with BMIPS you'd have > >> > to make it possible to define a new platform without the > >> > arch/mips/include/asm/mach-bmips/ directory (this should be possible > >> > already, so the hardest part is done), replace all global function > >> > calls (arch_init_irq, prom_init, get_system_type, ...) with generic > >> > platform-independent implementations or wrappers around per-platform > >> > callbacks, and move the Kconfig section for CONFIG_BMIPS_MULTIPLATFORM > >> > outside of the "System type" choice statement. > >> > >> Right. The other question is how much support for legacy non-DT > >> bootloaders really belongs in a true multiplatform kernel, as this > >> stuff gets hairy fast. > > > > Yes, that's why I suggested following PowerPC rather than ARM in this > > regard. If you move the boot loader abstraction into the decompressor > > instead of the platform code, you can avoid a lot of the problems. > > One possible complication: for BCM63xx/BCM7xxx (MIPS) there is no > decompressor in the kernel. The firmware loads an ELF image into > memory and jumps directly to kernel_entry. > Right, that complicates it a bit, but is there a reason why a decompressor would be hard to do, or would be considered a bad thing? There is already generic decompressor code in arch/mips/boot/compressed/ that I would assume you could use without firmware changes. Are you worried about boot time overhead? Arnd