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I'm not a CPU guy, so forgive me for asking what is probably a really dumb or unclear question, but given that Apple controls the whole stack, couldn't they jus

by MR4D 8y ago

I'm not a CPU guy, so forgive me for asking what is probably a really dumb or unclear question, but given that Apple controls the whole stack, couldn't they just remove the non-64 bit micro-code to save space? It seems like if it's doable, that Apple would do it - especially since they killed off 32-bit apps in iOS 11 already, and therefore were able to remove the 32-bit code from the iOS codebase too.

pjc50 8y ago
"Microcode" is the wrong word, it will be physical hardware on the chip, but yes - the sibling comment by jabl claims that some of the A64 chips had no 32-bit mode.
- ksec 8y ago
  >jabl claims that some of the A64 chips had no 32-bit mode. Fair Enough. [1] States it is AArch 64 only. I spent some time trying to find the official answer to AArch32 being optional, unfortunately nothing concrete has come up. [1] https://www.qualcomm.com/news/onq/2017/10/05/qualcomm-centriq-2400-designed-scalability-and-throughput-performance https://www.qualcomm.com/news/onq/2017/10/05/qualcomm-centri...
  - als0 8y ago
    The reference you're looking for is likely to be the ARMv8-A Architecture Reference Manual. For example, it mentions in multiple places "if AARCH32 is not implemented".