Hi, On 7/10/19 4:56 PM, Pavel Tatashin wrote: > On Wed, Jul 10, 2019 at 11:19 AM James Morse <james.morse@xxxxxxx> wrote: >> >> Hi Pasha, >> >> On 09/07/2019 14:07, Pavel Tatashin wrote: >>>>> Enabling MMU and D-Cache for relocation would essentially require the >>>>> same changes in kernel. Could you please share exactly why these were >>>>> not accepted upstream into kexec-tools? >>>> >>>> Because '--no-checks' is a much simpler alternative. >>>> >>>> More of the discussion: >>>> https://lore.kernel.org/linux-arm-kernel/5599813d-f83c-d154-287a-c131c48292ca@xxxxxxx/ >>>> >>>> While you can make purgatory a fully-fledged operating system, it doesn't really need to >>>> do anything on arm64. Errata-workarounds alone are a reason not do start down this path. >>> >>> Thank you James. I will summaries the information gathered from the >>> yesterday's/today's discussion and add it to the cover letter together >>> with ARM64 tag. I think, the patch series makes sense for ARM64 only, >>> unless there are other platforms that disable caching/MMU during >>> relocation. >> >> I'd prefer not to reserve additional memory for regular kexec just to avoid the relocation. >> If the kernel's relocation work is so painful we can investigate doing it while the MMU is >> enabled. If you can compare regular-kexec with kexec_file_load() you eliminate the >> purgatory part of the work. > > Relocation time is exactly the same for regular-kexec and > kexec_file_load(). So, the relocation is indeed painful for our case. > I am working on adding MMU enabled kernel relocation. Out of curiosity, does enabling only I-cache make a difference? IIRC, it doesn't require setting MMU, in contrast to D-cache. Cheers Vladimir > > Pasha > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
