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.
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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.”