Allow exposing the partitions tempfs to the outside

[wucke13]

Introduction

There should be a mode for the hypervisor which allows partitions the creation of files. Each / as perceived by the partition should map to a folder in the host environment, which might be determined by the CLI flag which enables the behavior.

Behavior

• Given the flag --partition-fs $PWD/part-fs is set while launching the hypervisor
• When the partition part_1 creates a file under /my-file (all as seen from the mnt namespace of part_1)
• Then this file should be visible on the host side (in the root mnt namespace) as $PWD/part-fs/part_1/my-file

Why?

I would like to use the hypervisor for instrumentation based coverage measurements. Most tools (like llvm-cov) rely on writing the coverage traces during runtime of the application to a file. If some sort of filesystem shared with host environment and the partitions is available, doing the instrumentation based coverage would be easy.

Caveat:

• What if the hypervisor quits, wouldn't that delete the tempfs of the partitions?
  • on quit, the hypervisor could move the files from all tempfs of the partitions to the actual destination
• How does this interact with the FS API mentioned in A653P2?
  • ???

[dadada]

The partition already has a root FS. If directories need to be shared with the outside, this can be done via bindmounts to paths inside it (e.g. `/var/coverage`. There is currently no way in the hypervisor to set up these bindmounts. But it should be possible to bindmount while it is running,either from inside the hypervisor or via `mount --bind`.

On June 2, 2023 5:10:44 PM GMT+02:00, wucke13 ***@***.***> wrote: ### Introduction There should be a mode for the hypervisor which allows partitions the creation of files. Each `/` as perceived by the partition should map to a folder in the host environment, which might be determined by the CLI flag which enables the behavior. ### Behavior - Given the flag `--partition-fs $PWD/part-fs` is set while launching the hypervisor - When the partition `part_1` creates a file under `/my-file` (all as seen from the mnt namespace of `part_1`) - Then this file should be visible on the host side (in the root mnt namespace) as `$PWD/part-fs/part_1/my-file` ### Why? I would like to use the hypervisor for instrumentation based coverage measurements. Most tools (like llvm-cov) rely on writing the coverage traces during runtime of the application to a file. If some sort of filesystem shared with host environment and the partitions is available, doing the instrumentation based coverage would be easy. ### Caveat: - What if the hypervisor quits, wouldn't that delete the tempfs of the partitions? - on quit, the hypervisor could move the files from all tempfs of the partitions to the actual destination - How does this interact with the FS API mentioned in A653P2? - ??? -- Reply to this email directly or view it on GitHub: #66 You are receiving this because you are subscribed to this thread. Message ID: ***@***.***>

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