On Mon, Aug 19, 2013 at 08:50:24PM +0100, M?ns Rullg?rd wrote:
Tom Rini trini@ti.com writes:
On 08/19/2013 01:33 PM, M?ns Rullg?rd wrote:
Scott Wood scottwood@freescale.com writes:
[snip]
i960 is a bad analogy. It's often possible to turn arm32 asm into arm64 asm with some search and replace and minor manual fixups.
Only if the original uses none of the distinguishing features of ARM like predicated instructions or variably shifted operands. Once you limit yourself to the remaining basic operations, every (RISC) architecture looks the same.
[snip]
AArch64 of course shares certain non-ISA aspects with AArch32. Page table formats and other architecturally defined system control features are the same, and code for managing these things should of course be shared. Some other features, e.g. exception handling, are different enough that sharing code is probably difficult.
There is a tendency to see arm64/aarch64 as yet another 64-bit extension of a 32-bit architecture, which it is not. Assuming that software support will or can follow the model used by the others mentioned is thus a mistake.
We don't have lots of hand-crafted assembly, and what we do, we largely have split out already into the cpu directories. I really think we just need to try this and see how it goes.
Fine, let's see what it ends up looking like.
That said, please consider naming things in a way that armv8 does not imply 64-bit.
Agreed, thanks!