Deepak Shetty <deepakcs@linux.vnet.ibm.com> Sent by: libvirt-cim-bounces@redhat.com
12/02/2011 05:13 AM
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Re: [Libvirt-cim] RFC : Introducing new CIM_RES_TYPE for 9pfs support on QEMU/KVM environment
On 12/02/2011 01:23 PM, Deepak Shetty wrote:
On 12/02/2011 04:32 AM, Sharad Mishra wrote: [...]
<filesystem type='mount'> <driver type='handle'/> <source dir='/tmp/virt1'/> <target dir='test-lib'/> <alias name='fs0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </filesystem>
What in the above libvirt XML makes it specific to 9pfs? I am looking for special 'tags' or 'properties'.
-Sharad Mishra type='mount' makes it specific to 9pfs. So its the type attribute of the filesystem tag. I confirmed the same by looking into libvirt code also.
[...]
The<filesystem> node comes directly under the<domain> node.
My approach for introducing 9pfs support in libvirt-cim is ...
1) Add a new CIM res type, eg; CIM_RES_TYPE_9PFS, is this ok ?
2) Add appropriate handlers for the above new resource type
3) Add new members in struct domain for representing this new device type. 4) Add appropriate xml parsing generation tags for the new resource type.
5) I probably need to add something like KVM_9PFSResourceAllocationSettingData -- I am not very clear on this yet. Need some help on how to do this ?
I found some more enlightment today looking at the code, so here are my newer thoughts...
1) It looks like the <filesystem> libvirt xml node ( that comes directly under <devices>) is supported in a psuedo fashion, under CIM_RES_TYPE_DISK, is this correct ? It does res_type = ...DISK and dev_type = ..DISK_FS.
That is right. So, a filesystem is a disk device with type set to DISK_FS.
2) The cim code is structured in such a way that for each device type that comes under <devices> there is a virt-device and <device_type>_device (eg: disk_device, net_device) structures and they are described by the respective RASDs. In following this tradition the there should have been virt_device and fs_device structures to correspond to the <filesystem> device type, eventually getting embedded under 'struct domain' but I don't see it, why is this so ? Why is <filesystem> treated differently in cim code ?
Not sure why its treated differently.
3) Assuming "yes" to #1 above, i need to extend the EmulatedType in KVM_DiskResourceAllocationSettingData to support "filesystem" as a value, set the disk_type = DISK_FS in disk_rasd_to_vdev and then it should probably work, as the disk_xml and disk_fs_xml code is already present to create the <filesystem> xml node.
Bulk of the code already exist. You may need to test it and fix some bugs.
4) I probably will re-use some of the members of KVM_DiskResourceAllocationSettingData from a 9pfs perspective, source and target will remain same as before, DriverCache, Address, may not be relevant for 9pfs. I might need to add few more stuff in DiskRASD as needed to support more sub-elements and attributes in for the <filesystem> in 9pfs case.
Depending on your requirement, you may have to add new properties. -Sharad
Let me know if the above approach/understanding is correct. Appreciate your inputs.
thanx, deepak
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