On Tue, Aug 18, 2020 at 03:07:04PM +0800, chenzhou wrote: > On 2020/8/10 14:03, Dave Young wrote: > >>> Previously I remember we talked about to use similar logic as X86, but I > >>> remember you mentioned on some arm64 platform there could be no low > >>> memory at all. Is this not a problem now for the fallback? Just be > >>> curious, thanks for the update, for the common part looks good. > >> > >> Did you mean this discuss: https://lkml.org/lkml/2019/12/27/122? > > I meant about this reply instead :) > > https://lkml.org/lkml/2020/1/16/616 > > Sorry for not repley in time, I was on holiday last week. > > The platform James mentioned may exist for which have no devices and > need no low memory. If there is no memory below 4GB, the arm64 kernel assumes that the 32-bit devices will have some DMA offsets shifting the addresses to the bottom of the available RAM. So even if RAM starts above 4GB, we ZONE_DMA32 will be allocated in the bottom 4GB of the high memory (and if the hardware designers forgot to shift those DMA accesses, we don't have to support the platform ;)). So the arm64 notion of low memory differs slightly from the x86 one. -- Catalin _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
