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Re: 9 TiB vm memory creation
From: |
David Hildenbrand |
Subject: |
Re: 9 TiB vm memory creation |
Date: |
Mon, 14 Feb 2022 15:37:53 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 |
On 14.02.22 13:36, Igor Mammedov wrote:
> On Mon, 14 Feb 2022 10:54:22 +0530 (IST)
> Ani Sinha <ani@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
>
> all of that on a host with 32G of RAM/no swap.
>
#define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)
~8 TiB (7,999999)
In QEMU, we have
static hwaddr kvm_max_slot_size = ~0;
And only s390x sets
kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES);
with
#define KVM_SLOT_MAX_BYTES (4UL * TiB)
--
Thanks,
David / dhildenb
- Re: 9 TiB vm memory creation, Igor Mammedov, 2022/02/14
- Re: 9 TiB vm memory creation,
David Hildenbrand <=
- Re: 9 TiB vm memory creation, Igor Mammedov, 2022/02/14
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15