From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751157Ab3LJXTJ (ORCPT ); Tue, 10 Dec 2013 18:19:09 -0500 Received: from ch1ehsobe006.messaging.microsoft.com ([216.32.181.186]:49922 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776Ab3LJXTF convert rfc822-to-8bit (ORCPT ); Tue, 10 Dec 2013 18:19:05 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -4 X-BigFish: VS-4(z579ehzbb2dI98dIc89bh936eI1432Izz1f42h2148h208ch1ee6h1de0h1fdah2073h2146h1202h1e76h2189h1d1ah1d2ah1fc6hzz1de098hz2dh2a8h839h93fhd24hf0ah1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh2222h224fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h2218h2216h226dh22d0h2327h2336h1155h) Message-ID: <1386717537.10013.150.camel@snotra.buserror.net> Subject: Re: [PATCH v2] powerpc 8xx: Loading kernels over 8Mbytes without CONFIG_PIN_TLB From: Scott Wood To: leroy christophe CC: Benjamin Herrenschmidt , Paul Mackerras , , Date: Tue, 10 Dec 2013 17:18:57 -0600 In-Reply-To: <52A79E31.9070304@c-s.fr> References: <20131210112945.E4E311A2BF3@localhost.localdomain> <1386714253.10013.123.camel@snotra.buserror.net> <52A79E31.9070304@c-s.fr> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% X-FOPE-CONNECTOR: Id%0$Dn%FREESCALE.MAIL.ONMICROSOFT.COM$RO%1$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-12-11 at 00:05 +0100, leroy christophe wrote: > Le 10/12/2013 23:24, Scott Wood a écrit : > > On Tue, 2013-12-10 at 12:29 +0100, Christophe Leroy wrote: > >> Today, the only way to load kernels whose size is greater than 8Mbytes is to > >> activate CONFIG_PIN_TLB. Otherwise, the physical memory initially mapped is > >> limited to 8Mbytes. This patch adds the capability to select the size of initial > >> memory between 8/16/24 Mbytes and this is regardless of whether CONFIG_PIN_TLB > >> is active or not. It allows to load "big" kernels (for instance when activating > >> CONFIG_LOCKDEP_SUPPORT) without having to activate CONFIG_PIN_TLB. > >> > >> Signed-off-by: Christophe Leroy > >> > >> diff -ur a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > >> --- a/arch/powerpc/Kconfig > >> +++ b/arch/powerpc/Kconfig > >> @@ -980,6 +980,29 @@ > >> config PIN_TLB > >> bool "Pinned Kernel TLBs (860 ONLY)" > >> depends on ADVANCED_OPTIONS && 8xx > >> + > >> +choice > >> + prompt "Initial Data Memory Mapped on 8xx" > >> + default 8xx_MAP_8M > >> + depends on ADVANCED_OPTIONS && 8xx > >> + > >> +config 8xx_INIT_MAP_8M > >> + bool "8 Mbytes" > >> + > >> +config 8xx_INIT_MAP_16M > >> + bool "16 Mbytes" > >> + > >> +config 8xx_INIT_MAP_24M > >> + bool "24 Mbytes" > > Are you working with a loader that passes initial-mapped-area size in r7 > > as per ePAPR? If so, we could rely on that at runtime. If you're using > > a non-ancient U-Boot, it should qualify here even if it's not fully > > ePAPR compliant (it passes the value of the bootm_mapsize variable in > > r7). > Ok, let me check that. But it means that the size of the kernel I can > boot will depend on the initial memory mapped by uboot ? Isn't it > limitating ? The ePAPR IMA is supposed to be large enough to include the OS image, device tree, etc. > Even if uboot only maps 8Mbytes, why couldn't I be allowed to boot a > kernel having 10 Mbytes data if I have 32 Mbytes mem on the board ? > I don't like the idea of having to change the bootloader just because I > want to activate CONFIG_LOCKDEP to debug my kernel. Well, as noted, if you're using a non-ancient U-Boot you shouldn't have to change anything because it already implements r7. Now, the value of r7 it passes might be a lie as far as ePAPR is concerned, since it's supposed to represent what's actually mapped, but that's another matter. Even fixing that wouldn't mean you have to change U-Boot every time the kernel size changes; you'd just set it to something reasonable and be done with it. I'm not fond of adding kconfigs to hack around a problem that has already been addressed in the standard that governs the PPC boot process that U-Boot claims to implement. > >> -#ifdef CONFIG_PIN_TLB > >> +#if defined (CONFIG_8xx_INIT_MAP_16M) || defined (CONFIG_8xx_INIT_MAP_24M) > >> /* Map two more 8M kernel data pages. > >> */ > >> +#ifdef CONFIG_PIN_TLB > >> addi r10, r10, 0x0100 > >> mtspr SPRN_MD_CTR, r10 > >> +#endif > >> > >> lis r8, KERNELBASE@h /* Create vaddr for TLB */ > >> addis r8, r8, 0x0080 /* Add 8M */ > >> @@ -858,15 +860,19 @@ > >> addis r11, r11, 0x0080 /* Add 8M */ > >> mtspr SPRN_MD_RPN, r11 > >> > >> +#ifdef CONFIG_8xx_INIT_MAP_24M > >> +#ifdef CONFIG_PIN_TLB > >> addi r10, r10, 0x0100 > >> mtspr SPRN_MD_CTR, r10 > >> +#endif > > Are these ifdefs for CONFIG_PIN_TLB really needed? It shouldn't harm > > anything to use those entries even if they're not being pinned. > > I'm not sure I understand your comment. > ifdef for CONFIG_PIN_TLB was already there before, but was enclosing the > whole block, so 24 Mbytes were automatically mapped when you selected > CONFIG_PIN_TLB and only 8 Mbytes were mapped when you didn't select > CONFIG_PIN_TLB. > I reduced the scope of those ifdefs so that they now apply on the > pinning only. There wasn't previously an ifdef specifically around the setting of SPRN_MD_CTR. That's new. There was an ifdef around the entire block, which has gone away because you are now trying to map more than 8M regardless of CONFIG_PIN_TLB, but that has nothing to do with whether there should be an ifdef around SPRN_MD_CTR. -Scott