Re: [PATCH] AARCH64: Change cpsr type to be 64bit.

[Yufeng Zhang <Yufeng dot Zhang at arm dot com>]

On 12/20/13 17:47, Pedro Alves wrote:
> On 12/18/2013 07:08 PM, Andrew Pinski wrote:
> > As mentioned in http://www.spinics.net/lists/arm-kernel/msg290896.html, we should change gdb's notion of cpsr to be 64bit.
> >
> > OK?  Build and tested for aarch64-linux-gnu with no regressions.
> > I also double checked to make sure that what is passed down from the kernel (via sigcontext), is the full 64bit.
>
> With this, the register will be exposed as 64-bit to the
> user.  Is that desirable?  The fact that the original
> description used 32-bit makes it sounds like it's not.
> What's the real register width at the (asm visible)
> machine level?

There is no access to CPSR as a single register in AArch64 (*). 
Instead, process states can be accessed/modified via system 
instructions.  I guess the kernel synthesizes one CPSR register, so if 
kernel defines it as a 64-bit register, it is reasonable for gdb to 
treat it of the same size as well.

Yufeng


Reference:

* ARMv8 Instruction Set Overview - Chapter 3 A64 Overview