On 2022/4/26 22:26, Catalin Marinas wrote: > On Thu, Apr 14, 2022 at 07:57:15PM +0800, Zhen Lei wrote: >> @@ -540,13 +540,31 @@ static void __init map_mem(pgd_t *pgdp) >> for_each_mem_range(i, &start, &end) { >> if (start >= end) >> break; >> + >> +#ifdef CONFIG_KEXEC_CORE >> + if (eflags && (end >= SZ_4G)) { >> + /* >> + * The memory block cross the 4G boundary. >> + * Forcibly use page-level mappings for memory under 4G. >> + */ >> + if (start < SZ_4G) { >> + __map_memblock(pgdp, start, SZ_4G - 1, >> + pgprot_tagged(PAGE_KERNEL), flags | eflags); >> + start = SZ_4G; >> + } >> + >> + /* Page-level mappings is not mandatory for memory above 4G */ >> + eflags = 0; >> + } >> +#endif > > That's a bit tricky if a SoC has all RAM above 4G. IIRC AMD Seattle had > this layout. See max_zone_phys() for how we deal with this, basically > extending ZONE_DMA to the whole range if RAM starts above 4GB. In that > case, crashkernel reservation would fall in the range above 4GB. > > BTW, we changed the max_zone_phys() logic with commit 791ab8b2e3db > ("arm64: Ignore any DMA offsets in the max_zone_phys() calculation"). Okay, thanks for your correction. I'll dig into it after I've done the original requirement. > -- Regards, Zhen Lei _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec