Apple Plans to Use Its Own Chips in Macs from 2020, Replacing Intel

Re:Apple Plans to Use Its Own Chips in Macs from 2020, Repla... by Someone on Monday April 02, 2018 @06:42PM (#16740142)

…or you design your own ARM CPU that handles unaligned memory accesses fine, and run your emulator on that hardware.

[ Parent | on HN ]

Re:Apple Plans to Use Its Own Chips in Macs from 2020, Repla... by readittwice on Tuesday April 03, 2018 @09:29AM (#16744398)

AFAIK the ARM license doesn't allow to invent arbitrary extensions to the ISA. So this might not be allowed.

[ Parent | on HN ]

Re:Apple Plans to Use Its Own Chips in Macs from 2020, Repla... by Someone on Tuesday April 03, 2018 @12:34PM (#16746369)

Apple has an architectural license. I would expect that allows them to add instructions (assuming modern ARM still has the concept of instruction set extensions)

Google didn’t answer that for me, but I found out that there now is a ”cp15 sctlr[1] (alignment bit)”. http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.... says this about it:

”3.5.1. Alignment faults

If alignment fault checking is enabled (the A bit in CP15 c1 is set), the MMU generates an alignment fault on any data word access if the address is not word-aligned, or on any halfword access if the address is not halfword-aligned, irrespective of whether the MMU is enabled or not. An alignment fault is not generated on any instruction fetch or any byte access.”

[ Parent | on HN ]