On Thu, Oct 17, 2024 at 02:07:12PM +0200, David Hildenbrand wrote: > On 17.10.24 12:00, David Hildenbrand wrote: > > Well, DIAGNOSE 260 is z/VM only and DIAG 500 is KVM only. So there are > > currently not really any other reasonable ways besides SCLP. > > Correction: Staring at the code again, in detect_physmem_online_ranges() > we will indeed try: > > a) sclp_early_read_storage_info() > b) diag260() So why care to call diag260() in case of DIAGNOSE 500? What about the below? void detect_physmem_online_ranges(unsigned long max_physmem_end) { if (!sclp_early_read_storage_info()) { physmem_info.info_source = MEM_DETECT_SCLP_STOR_INFO; } else if (physmem_info.info_source == MEM_DETECT_DIAG500_STOR_LIMIT) { unsigned long online_end; if (!sclp_early_get_memsize(&online_end)) { physmem_info.info_source = MEM_DETECT_SCLP_READ_INFO; add_physmem_online_range(0, online_end); } } else if (!diag260()) { physmem_info.info_source = MEM_DETECT_DIAG260; } else if (max_physmem_end) { add_physmem_online_range(0, max_physmem_end); } } > But if neither works, we cannot blindly add all that memory, something is > messed up. So we'll fallback to > > c) sclp_early_get_memsize() > > But if none of that works, something is seriously wrong. Ok, thanks for the clarification.