Re: [Qemu-devel] [PATCH 2/4] tcg/aarch64: implement new TCG target for aarch64

[Peter Maydell]

On 24 May 2013 18:17, Richard Henderson <address@hidden> wrote:
> On 05/24/2013 10:08 AM, Peter Maydell wrote:
>> Where's the waste? The procedure calling standard mandates that we
>> set FP up, so it's not like we can use it as a general purpose
>> register anywhere.
>
> Well, the calling standard is another document that's not available
> yet

Nope, it's been available for ages, along with the ELF and DWARF
specs and the C++ ABI:
  
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ihi0055b/index.html

> so obviously I don't know the rationale for that decision.  But
> it does seem like a register performing no useful function...

It does what a frame pointer usually does, ie permits the debugger
(and other tools) to unwind the stack.

thanks
-- PMM