Re: Recommended HBA management interfaces

James Smart
2009-07-21T12:29:27Z

Mukker, Atul wrote:
> The management protocol involves significant amount of binary data transfer involving multiple applications, so sysfs and friends are not useful for this particular application. But I gather from your (and Brian's) email that mid-layer SG extension should be used for this particular purpose.
>
> As for asynchronous notifications, netlink seems to be the de-facto choice (or it's mid-layer extensions). But didn't you mention earlier, vmware would not support this?

I answered from a purely linux perspective. VMware is not Linux. VMware
attempts to emulate the linux driver/midlayer api's, but emulation is done in
their own way, with their own semantics, for their own purposes.. Anyone that
believes they just drop a linux driver into vmware and it works w/o change has
a screw loose. It may appear to work, and some subsystems may be better than
others, but there are very subtle and critical differences. As for all the
ancillary interfaces such as sysfs, sgio, and transports: a) they have a hard
time keeping up with the pace of the linux kernel; b) many of the interfaces
are anti their hypervisor management model. Dependence on user-space utils,
sysfs, etc doesn't work with a cos-less environment. Netlink and sockets
opens up security holes, and hypervisor-level socket support brings all kinds
of headaches and memory issues. Netlink is not supported. Sysfs isn't
supported. Even portions of the transports/midlayer are only partially
implemented. Unfortunately, vmware interfaces need to be taken up with vmware.

-- james s