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docs: Update snapshot/restore documentation

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Remove the bits about this feature being experimental, as well as
limitations around virtio-mem and vhost-user devices.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2022-02-07 11:00:57 +01:00 committed by Rob Bradford
parent 85f5364594
commit b552aebbd4
1 changed files with 3 additions and 22 deletions
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docs/snapshot_restore.md
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@ -8,9 +8,6 @@ snapshot and creates the exact same virtual machine, restoring the previously
saved states. The new virtual machine is restored in a paused state, as it was
before the snapshot was performed.
This feature is important for the project as it establishes the first step
towards the support for live migration.
## Snapshot a Cloud Hypervisor VM
First thing, we must run a Cloud Hypervisor VM:
@ -46,18 +43,11 @@ ll /home/foo/snapshot/
total 4194536
drwxrwxr-x 2 foo bar 4096 Jul 22 11:50 ./
drwxr-xr-x 47 foo bar 4096 Jul 22 11:47 ../
-rw------- 1 foo bar 3221225472 Jul 22 11:19 memory-region-0
-rw------- 1 foo bar 1073741824 Jul 22 11:19 memory-region-1
-rw------- 1 foo bar 4294967296 Jul 22 11:19 memory-ranges
-rw------- 1 foo bar 217853 Jul 22 11:19 vm.json
```
In this particular example, we can observe that 2 memory region files were
created. That is explained by the size of the guest RAM, which is 4GiB in this
case. Because it exceeds 3GiB (which is where we can find a ~1GiB memory hole),
Cloud Hypervisor needs 2 distinct memory regions to be created. Each memory
region's content is stored through a dedicated file, which explains why we end
up with 2 different files, the first one containing the guest RAM range 0-3GiB
and the second one containing the guest RAM range 3-4GiB.
`memory-ranges` stores the content of the guest RAM.
`vm.json` gathers all information related to the virtual machine configuration
and state. The configuration bits are used to create a similar virtual machine
@ -100,13 +90,4 @@ snapshot earlier.
## Limitations
The support of snapshot/restore feature is still experimental, meaning one
might still find some bugs associated with it.
Additionally, some devices and features don't support to be snapshot and
restored yet:
- `vhost-user` devices
- `virtio-mem`
- Intel SGX
VFIO devices are out of scope.
VFIO devices and Intel SGX are out of scope.