On 15.02.22 08:00, Ani Sinha wrote: > > > On Mon, 14 Feb 2022, David Hildenbrand wrote: > >> On 14.02.22 13:36, Igor Mammedov wrote: >>> On Mon, 14 Feb 2022 10:54:22 +0530 (IST) >>> Ani Sinha <a...@anisinha.ca> wrote: >>> >>>> Hi Igor: >>>> >>>> I failed to spawn a 9 Tib VM. The max I could do was a 2 TiB vm on my >>>> system with the following commandline before either the system >>>> destabilized or the OOM killed killed qemu >>>> >>>> -m 2T,maxmem=9T,slots=1 \ >>>> -object >>>> memory-backend-file,id=mem0,size=2T,mem-path=/data/temp/memfile,prealloc=off >>>> \ >>>> -machine memory-backend=mem0 \ >>>> -chardev file,path=/tmp/debugcon2.txt,id=debugcon \ >>>> -device isa-debugcon,iobase=0x402,chardev=debugcon \ >>>> >>>> I have attached the debugcon output from 2 TiB vm. >>>> Is there any other commandline parameters or options I should try? >>>> >>>> thanks >>>> ani >>> >>> $ truncate -s 9T 9tb_sparse_disk.img >>> $ qemu-system-x86_64 -m 9T \ >>> -object >>> memory-backend-file,id=mem0,size=9T,mem-path=9tb_sparse_disk.img,prealloc=off,share=on >>> \ >>> -machine memory-backend=mem0 >>> >>> works for me till GRUB menu, with sufficient guest kernel >>> persuasion (i.e. CLI limit ram size to something reasonable) you can boot >>> linux >>> guest on it and inspect SMBIOS tables comfortably. >>> >>> >>> With KVM enabled it bails out with: >>> qemu-system-x86_64: kvm_set_user_memory_region: >>> KVM_SET_USER_MEMORY_REGION failed, slot=1, start=0x100000000, >>> size=0x8ff40000000: Invalid argument >>> > > I have seen this in my system but not always. Maybe I should have dug > deeper as to why i do see this all the time. > >>> all of that on a host with 32G of RAM/no swap. >>> > > My system in 16 Gib of main memory, no swap. > >> >> #define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1) >> >> ~8 TiB (7,999999) > > That's not 8 Tib, thats 2 GiB. But yes, 0x8ff40000000 is certainly greater > than 2 Gib * 4K (assuming 4K size pages).
"pages" don't carry the unit "GiB/TiB", so I was talking about the actual size with 4k pages (your setup, I assume) -- Thanks, David / dhildenb