Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756886AbZCCCy3 (ORCPT ); Mon, 2 Mar 2009 21:54:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752869AbZCCCyU (ORCPT ); Mon, 2 Mar 2009 21:54:20 -0500 Received: from hera.kernel.org ([140.211.167.34]:39804 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359AbZCCCyT (ORCPT ); Mon, 2 Mar 2009 21:54:19 -0500 Message-ID: <49AC9B99.5020000@kernel.org> Date: Mon, 02 Mar 2009 18:53:13 -0800 From: Yinghai Lu User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Huang Ying CC: Brian Maly , Ingo Molnar , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] Fix e820 end address with EFI References: <49A965AD.10701@redhat.com> <86802c440902282142p14f623b8td8a88600ff2a6bbe@mail.gmail.com> <49AAEC79.3000808@redhat.com> <1235956068.6204.143.camel@yhuang-dev.sh.intel.com> <49AB38E7.60305@redhat.com> <1235960016.6204.170.camel@yhuang-dev.sh.intel.com> <49AB4171.7000508@kernel.org> <1235960708.6204.176.camel@yhuang-dev.sh.intel.com> <49AB4521.8010909@kernel.org> <1235961428.6204.190.camel@yhuang-dev.sh.intel.com> <86802c440903011851t17e240eu9dc25116a40ca85e@mail.gmail.com> <1235979959.6204.212.camel@yhuang-dev.sh.intel.com> <49AC51D7.1080203@kernel.org> <1236042459.6204.226.camel@yhuang-dev.sh.intel.com> <49AC87AE.60001@kernel.org> <1236046936.6204.243.camel@yhuang-dev.sh.intel.com> In-Reply-To: <1236046936.6204.243.camel@yhuang-dev.sh.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3089 Lines: 73 Huang Ying wrote: > On Tue, 2009-03-03 at 09:28 +0800, Yinghai Lu wrote: >> Huang Ying wrote: >>> On Tue, 2009-03-03 at 05:38 +0800, Yinghai Lu wrote: >>>> Huang Ying wrote: >>>>> On Mon, 2009-03-02 at 10:51 +0800, Yinghai Lu wrote: >>>>>> On Sun, Mar 1, 2009 at 6:37 PM, Huang Ying wrote: >>>>>>>> so 64bit could use ioremap_cache() too? >>>>>>>> we may keep 32bit and 64bit a bit consistent. >>>>>>> If we use ioremap_cache(), kexec runtime service will not work in kexec >>>>>>> situation, which needs EFI runtime memory area to be mapped at exact >>>>>>> same location across kexec. I think we should support kexec if possible. >>>>>> sure. >>>>>> >>>>>> please don't touch max_low_pfn_mapped, because some range may not >>>>>> directly mapped under those efi run-time code >>>>> Find an issue to use init_memory_mapping() here. >>>>> >>>>> If the memory range to be mapped is less than 2M, the last mapped >>>>> address may be next 2M aligned position, this may lead mapping >>>>> overlapping between memory range. Such as: >>>>> >>>>> 0x3f388000 - 0x3f488000: real mapped 0x3f388000 - 0x3f600000 >>>>> 0x3f590000 - 0x3f5bb000: real mapped 0x3f590000 - 0x3f600000 >>>>> >>>>> The problem is that the memory range 0x3f400000 - 0x3f590000 is left not >>>>> mapped! >>>> what is max_low_pfn_mapped before that? >>> I don't know exactly what you mean. Can you elaborate a little? >>> >>> 0 ~ max_low_pfn_mapped ~ max_pfn_mapped can be mapped with >>> init_memory_mapping() properly. >>> >>> The issue of above example is that 0x3f400000 ~ 0x3f488000 is a >>> sub-range of 0x3f388000 ~ 0x3f488000, which should be mapped but is left >>> not mapped. >> what is max_low_pfn_mapped? >> >> what is init_memory_mapping() printout? > > This does not comes from a real test case. To test the changes I made, I > make efi_ioremap() being used even if the corresponding memory range is > below max_low_pfn_mapped. The dmesg of test is attached with the mail. > > The printout of init_memory_mapping shows: > > init_memory_mapping: 000000003f488000-000000003f4bb000 > last_map_addr: 3f600000 end: 3f4bb000 > init_memory_mapping: 000000003f590000-000000003f5bb000 > last_map_addr: 3f600000 end: 3f5bb000 init_memory_mapping: 0000000000000000-000000003f700000 last_map_addr: 3f700000 end: 3f700000 (6 early reservations) ==> bootmem [0000000000 - 003f700000] so max_low_pfn_mapped is (3f700000>>12) and you try to init_memory_mapping again before it > init_memory_mapping: 00000000fffb0000-00000000fffba000 > last_map_addr: 100000000 end: fffba000 this one is interesting... got over mapped... > > So I think it is possible to have the issue I mentioned above. looks like. YH -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/