A processor, comprising: a mapping module and a translation-lookaside buffer; characterised in that: the mapping module is configured to map architectural virtual processor identifiers (254; 1008) to non-architectural global identifiers and to map architectural process context identifiers (252; 908) to non-architectural local identifiers, so that the global and local identifiers uniquely identify entries in at least one context table (212, 214) from which the virtual processor identifiers (254; 1008) and process context identifiers (252; 908) can be retrieved; and the translation-lookaside buffer is configured to have a plurality of address translations, wherein for each address translation of the plurality of address translations: when the address translation is a global address translation, the address translation is tagged with a representation of one of the non-architectural global identifiers to which the mapping module has mapped one of the virtual processor identifiers (254; 1008); and when the address translation is a local address translation, the address translation is tagged with a representation of one of the non-architectural local identifiers to which the mapping module has mapped one of the process context identifiers (252; 908). a mapping module and a translation-lookaside buffer; characterised in that: the mapping module is configured to map architectural virtual processor identifiers (254; 1008) to non-architectural global identifiers and to map architectural process context identifiers (252; 908) to non-architectural local identifiers, so that the global and local identifiers uniquely identify entries in at least one context table (212, 214) from which the virtual processor identifiers (254; 1008) and process context identifiers (252; 908) can be retrieved; and the translation-lookaside buffer is configured to have a plurality of address translations, wherein for each address translation of the plurality of address translations: when the address translation is a global address translation, the address translation is tagged with a representation of one of the non-architectural global identifiers to which the mapping module has mapped one of the virtual processor identifiers (254; 1008); and when the address translation is a local address translation, the address translation is tagged with a representation of one of the non-architectural local identifiers to which the mapping module has mapped one of the process context identifiers (252; 908). the mapping module is configured to map architectural virtual processor identifiers (254; 1008) to non-architectural global identifiers and to map architectural process context identifiers (252; 908) to non-architectural local identifiers, so that the global and local identifiers uniquely identify entries in at least one context table (212, 214) from which the virtual processor identifiers (254; 1008) and process context identifiers (252; 908) can be retrieved; and the translation-lookaside buffer is configured to have a plurality of address translations, wherein for each address translation of the plurality of address translations: when the address translation is a global address translation, the address translation is tagged with a representation of one of the non-architectural global identifiers to which the mapping module has mapped one of the virtual processor identifiers (254; 1008); and when the address translation is a local address translation, the address translation is tagged with a representation of one of the non-architectural local identifiers to which the mapping module has mapped one of the process context identifiers (252; 908). when the address translation is a global address translation, the address translation is tagged with a representation of one of the non-architectural global identifiers to which the mapping module has mapped one of the virtual processor identifiers (254; 1008); and when the address translation is a local address translation, the address translation is tagged with a representation of one of the non-architectural local identifiers to which the mapping module has mapped one of the process context identifiers (252; 908).