1. Apparatus for processing data comprising: translation buffer circuitry to store translation data to translate an input address of a memory access transaction to an output address; and translation control circuitry to provide said translation data to said translation buffer circuitry, wherein said translation buffer circuitry is responsive to receipt of a memory access transaction for which translation data is unavailable in said translation buffer circuitry to issue a request to said translation control circuitry to provide translation data for said memory access transaction; said translation control circuitry is responsive to a change in enablement of address translation for a given type of memory access transaction to issue an invalidate command to said translation buffer circuitry to invalidate any translation data for said given type of memory access transaction stored in said translation buffer circuitry; and said translation control circuitry is responsive to receipt of a request for translation data from said translation buffer circuitry for a memory access of said given type for which memory address translation is disabled to return global translation data to be used by said translation buffer circuitry for all memory access transactions of said given type.
1. Apparatus for processing data comprising: translation buffer circuitry to store translation data to translate an input address of a memory access transaction to an output address; and translation control circuitry to provide said translation data to said translation buffer circuitry, wherein said translation buffer circuitry is responsive to receipt of a memory access transaction for which translation data is unavailable in said translation buffer circuitry to issue a request to said translation control circuitry to provide translation data for said memory access transaction; said translation control circuitry is responsive to a change in enablement of address translation for a given type of memory access transaction to issue an invalidate command to said translation buffer circuitry to invalidate any translation data for said given type of memory access transaction stored in said translation buffer circuitry; and said translation control circuitry is responsive to receipt of a request for translation data from said translation buffer circuitry for a memory access of said given type for which memory address translation is disabled to return global translation data to be used by said translation buffer circuitry for all memory access transactions of said given type. 6. Apparatus as claimed in claim 1 , wherein said memory access transaction has an associated attribute indicating said memory access transaction is a pre-translated memory access transaction that has already been subject to an address translation, said transaction control circuitry is responsive to a change of enablement of translation for said pre-translated memory access translations to invalidate any translation data stored in said translation buffer circuitry for said pre-translated memory access transactions, and said global translation data is used by said translation buffer circuitry for all pre-translated memory access translation for which translation is disabled.