On Mon, 2018-07-23 at 13:53 -0700, Tadeusz Struk wrote: > On 07/23/2018 01:19 PM, Jarkko Sakkinen wrote: > > In this case I do not have any major evidence of any major benefit > > *and* the change breaks the ABI. > > As I said before - this does not break the ABI. The current patch does, you even provided a use case in your last email (it's do command to get sizing followed by do command with correctly sized buffer). However, if you tie it to O_NONBLOCK, it won't because no-one currently opens the TPM device non blocking so it's an ABI conformant discriminator of the uses. Tying to O_NONBLOCK should be simple because it's in file->f_flags. James