Messages in this thread | | | Subject | Re: [PATCH] tpm: add support for partial reads | From | Tadeusz Struk <> | Date | Thu, 19 Jul 2018 13:12:19 -0700 |
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On 07/19/2018 12:52 PM, James Bottomley wrote: > The ABI break is the error case as I outlined above. We can't assume > everyone uses the current interface without getting an error and one > error and your hosed is a nasty failure case to change the interface > to.
Well, if there is a broken application out there that doesn't work today it will not work after this change neither.
> Plus, if you assume everyone is passing 4k buffers, why would you > even need the fragmentation case?
So that people don't need to do this anymore and we can run a spec compliant TCTI on top of /dev/tpm<N>.
> >>> It might be possible to layer the behaviour you want compatibly >>> into the current device structure (say an ioctl to switch to the >>> fragment behaviour) but I've got to ask why we'd go to the >>> complexity without a use case? >> New IOCTL would add extra complexity, which isn't necessary. > So what's wrong with fragmenting in the layer above the device driver > (in userspace) and not actually changing the kernel?
Because it is much easier to implement in the driver, and we can run a spec compliant TCTI on top of /dev/tpm<N>.
Thanks, -- Tadeusz
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