On Wed, Aug 19, 2020 at 12:57:42PM -0400, Mimi Zohar wrote: > On Wed, 2020-08-19 at 13:18 -0300, Jason Gunthorpe wrote: > > Yes - it was dropped because TPM 2 was a *complete ABI break* for > > everything. The kernel was reset to a uABI that matches current > > uABI standards starting TPM 2. > > > > The whole userspace needed to be redone anyhow, and certainly nobody > > objected at the time. > > > > At least my expecation was that a sensible userspace for TPM (for > > administrator user) would be built, like we see in other subsystems eg > > 'ip' for netdev. > > "Because TPM 2 was a complete ABI break for everything" could be reason > for upstreaming a minimal subset of functionality initially, which > could be expanded over time. I don't recall a discussion about limting > features in the future. All new uAPI additions need to pass the usual uAPI hurdles. As James outlined, justify why the kernel must present a duplicated uAPI between sysfs and /dev/tpm. There have been good reasons in the past, eg SCSI inquiry. But there are also bad reasons like "our userpsace is dysfunctional and can't make a library or tool". Jason
