On 06/30/2020 02:10 PM, Hari Bathini wrote: > > > On 30/06/20 9:00 am, piliu wrote: >> >> >> On 06/29/2020 01:55 PM, Hari Bathini wrote: >>> >>> >>> On 28/06/20 7:44 am, piliu wrote: >>>> Hi Hari, >>> >>> Hi Pingfan, >>> >>>> >>>> After a quick through for this series, I have a few question/comment on >>>> this patch for the time being. Pls see comment inline. >>>> >>>> On 06/27/2020 03:05 AM, Hari Bathini wrote: >>>>> crashkernel region could have an overlap with special memory regions >>>>> like opal, rtas, tce-table & such. These regions are referred to as >>>>> exclude memory ranges. Setup this ranges during image probe in order >>>>> to avoid them while finding the buffer for different kdump segments. >>> >>> [...] >>> >>>>> + /* >>>>> + * Use the locate_mem_hole logic in kexec_add_buffer() for regular >>>>> + * kexec_file_load syscall >>>>> + */ >>>>> + if (kbuf->image->type != KEXEC_TYPE_CRASH) >>>>> + return 0; >>>> Can the ranges overlap [crashk_res.start, crashk_res.end]? Otherwise >>>> there is no requirement for @exclude_ranges. >>> >>> The ranges like rtas, opal are loaded by f/w. They almost always overlap with >>> crashkernel region. So, @exclude_ranges is required to support kdump. >> f/w passes rtas/opal as service, then must f/w mark these ranges as >> fdt_reserved_mem in order to make kernel aware not to use these ranges? > > It does. Actually, reserve_map + reserved-ranges are reserved as soon as > memblock allocator is ready but not before crashkernel reservation. > Check early_reserve_mem() call in kernel/prom.c > >> Otherwise kernel memory allocation besides kdump can also overwrite >> these ranges.> >> Hmm, revisiting reserve_crashkernel(). It seems not to take any reserved >> memory into consider except kernel text. Could it work based on memblock >> allocator? > > So, kdump could possibly overwrite these regions which is why an exclude > range list is needed. Same thing was done in kexec-tools as well. OK, got it. Thanks, Pingfan > > Thanks > Hari > > _______________________________________________ > kexec mailing list > kexec@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/kexec > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
