Support persistent memory volumes #2515
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@jodh-intel @amshinde @pohly @bergwolf @lifupan please take a look |
| // getBackingFile is used to fetch the backing file for the device. | ||
| func getBackingFile(devInfo DeviceInfo) (string, error) { | ||
| backingFilePath := filepath.Join(getSysDevPath(devInfo), "loop", "backing_file") | ||
| if _, err := os.Stat(backingFilePath); err != nil { |
There was a problem hiding this comment.
You could remove the Stat by checking the error from ReadFile() using os.IsNotExist(err).
bring `pmem` option to pmem/nvdimm devices shortlog: qemu: add pmem flag to memory-backend-file Signed-off-by: Julio Montes <julio.montes@intel.com>
`GetDevicePathAndFsType` is a function to get the path and filesystem type of a mount point from `/proc/mounts`. Move `GetDevicePathAndFsType` to utils_linux since it's linux specific and that way it can be used in other subpackages. Signed-off-by: Julio Montes <julio.montes@intel.com>
Implement function the get the backing file from a loop device. The backing file can be used as backend file for a NVDIMM device in the guest Signed-off-by: Julio Montes <julio.montes@intel.com>
Implement function to get the pmem `DeviceInfo` from a volume. `PmemDeviceInfo` return a new `DeviceInfo` object if a volume has a loop device as backend and the backing file for such loop device contains the PFN signature, needed to enable DAX in the guest. Signed-off-by: Julio Montes <julio.montes@intel.com>
A `BlockDrive` can be used as pmem device, since they both are similar and can be mounted in the same way in the guest. The `Pmem` attribute helps kata to identify a pmem device and how it has to be hotplugged in the guest. Signed-off-by: Julio Montes <julio.montes@intel.com>
Reimplement `createBlockDevices` to identify possible volumes that can be used as pmem devices Signed-off-by: Julio Montes <julio.montes@intel.com>
hotplug as NVDIMM devices the block drives that can be used as pmem devices (`Pmem=true`), the host path to such devices is a raw file that contains the PFN signature. Signed-off-by: Julio Montes <julio.montes@intel.com>
A persistent memory volume MUST meet the following conditions: * A loop device must be mounted in the directory passed as volume * The loop device must have a backing file * The backing file must have the PFN signature at offset 4k [1][2] The backing file is used as backend file for a NVDIMM device in the guest fixes kata-containers#2262 [1] - https://github.com/kata-containers/osbuilder/blob/master/image-builder /nsdax.gpl.c [2] - https://github.com/torvalds/linux/blob/master/drivers/nvdimm/pfn.h Signed-off-by: Julio Montes <julio.montes@intel.com>
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@jodh-intel change applied, thanks |
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This all looks reasonable to me, with the caveat of course that I don't know the code base. For user-facing documentation we can use the PMEM-CSI project, because that is what users will have to start with to use the new feature. I can also add end-to-end testing there once there is release of Kata Containers with this feature. Are you doing canary builds, i.e. once this is merged, can I directly install a pre-release of Kata Containers which supports PMEM? |
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@pohly sure, you can download the static tarball form here https://github.com/kata-containers/runtime/releases/ |
Can you ping me when there's an alpha with this feature included? |
sure thing 👍 |
A persistent memory volume MUST meet the following conditions:
The backing file is used as backend file for a NVDIMM device in the guest
fixes #2262
[1] - https://github.com/kata-containers/osbuilder/blob/master/image-builder
/nsdax.gpl.c
[2] - https://github.com/torvalds/linux/blob/master/drivers/nvdimm/pfn.h
cc @pohly
Signed-off-by: Julio Montes julio.montes@intel.com