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| -rw-r--r-- | docs/components/el3-spmc.rst | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/docs/components/el3-spmc.rst b/docs/components/el3-spmc.rst index fd5324a1c..b461eeff4 100644 --- a/docs/components/el3-spmc.rst +++ b/docs/components/el3-spmc.rst @@ -227,10 +227,16 @@ The following additional interfaces are forwarded from SPMD to support NS Client FFA_VERSION ----------- - -``FFA_VERSION`` requires a *requested_version* parameter from the caller. -SPMD forwards call to SPMC, the SPMC returns its own implemented version. -SPMC asserts SP and SPMC are at same FF-A Version. +For a normal-world endpoint, ``FFA_VERSION`` takes the caller's +*requested_version*. The SPMD forwards the call to the SPMC, which returns +its implemented version. If the requested version is compatible, the SPMC +records it as the endpoint's negotiated version. + +Once an endpoint invokes any FF-A ABI other than ``FFA_VERSION``, version +negotiation is complete and its version cannot be changed for the endpoint's +lifetime. A normal-world endpoint must therefore successfully invoke +``FFA_VERSION`` before invoking another FF-A ABI. An SP's initial version is +obtained from and validated against its manifest. FFA_FEATURES ------------ |