it look like Apple is allowed to add proprietary ISA extensions according to Asahi Linux.
Apple's ARM license is beyond architectural?
- Thread starter soAsian
- Start date
it look like Apple is allowed to add proprietary ISA extensions according to Asahi Linux.
M
mgoldsmith1979
Guest
I don't think this is as unique to Apple as the poster implies. Intel added MMX to their StrongARM before standard ARM cores added NEON (VFP/SIMD). Qualcomm's implementation of NEON was VeNum (IIRC) and while this was high level the same, there were some differences. What has been novel in the more recent deployments from ARM (the "built-on-Cortex" and custom instructions in the CMx family) are that ARM themselves are allowing extension of their own CPU implementation to include ISA extensions by a customer (in the former) or they are adding customer ISA extensions to the core IP (in the latter). But other players have had ISA extensions on ARM Av5/6/7 cores in the past, not just Apple, so I don't believe the Arch license is as restrictive as they imply. Yes, you have to pass a verification step to ensure that your implementation is ISA compliant, but that doesn't exclude the use of reserved space (just no guarantee to be forward compatible). With introduction of Android and GCC-binary distribution of the OS / apps / etc there is little benefit to these custom ISA extensions because they are never called by the compiler; hence the base ISA carries the brunt of the value.
it look like Apple is allowed to add proprietary ISA extensions according to Asahi Linux.