Re: [Qemu-devel] [PATCH] microblaze: Remove uses of TCGv and target_ulong

[Richard Henderson <rth@twiddle.net>]

On 05/15/2015 09:48 AM, Peter Crosthwaite wrote:
> On Fri, May 15, 2015 at 8:41 AM, Richard Henderson <rth@twiddle.net> wrote:
>> On 05/14/2015 09:49 PM, Peter Crosthwaite wrote:
>>> To prepare support for conversion of Microblaze TARGET_LONG to 64 bits.
>>> This in turn will then allow support for multi-arch QEMU including both
>>> Microblaze and 64-bit CPU targets (notably AArch64).
>>
>> I don't understand why multi-arch requires all of the arches
>> to have the same width.  This seems like a major failure to me.
>>
>> I'm not particularly keen on this at all.
>>
> 
> What is the alternative? What is the def of the global symbols TCGv
> and TARGET_LONG in the multi-arch cases?

Different for every file?  Not relevant for "multi-arch" itself?
I dunno.  Where does stuff break down first?

I would expect 80% of it to be private to target-foo, and /mostly/ encapsulated
in the tcg ops that are produced.

I realize there's a problem of how addresses are treated inside the tcg
backend, but that should be surmountable.  Perhaps all we need are 4 new
opcodes so that both 32-bit and 64-bit addresses can be represented within the
opcode stream simultaneously.

I assume we're not still talking about multi-arch linux-user, but are really
only talking about softmmu here...


r~