On Thu, Jul 11, 2019 at 4:12 AM Vladimir Murzin <vladimir.mur...@arm.com> wrote: > > Hi, > > On 7/10/19 4:56 PM, Pavel Tatashin wrote: > > On Wed, Jul 10, 2019 at 11:19 AM James Morse <james.mo...@arm.com> 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-c131c4829...@arm.com/ > >>>> > >>>> 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.
Resend: Thank you for suggestion. I have actually experimented with enabling caches without MMU. Did not see a difference. Thank you, Pasha > > Cheers > Vladimir > > > > > Pasha > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-ker...@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > >
