Re: [Qemu-devel] [PATCH v5 07/18] qemu-thread: add simple test-and-set spinlock

[Peter Maydell]

On 18 May 2016 at 16:36, Paolo Bonzini <address@hidden> wrote:
> On 18/05/2016 17:35, Peter Maydell wrote:
>>> > $ arm-linux-gnueabi-gcc -march=armv6 -O2 -c a.c
>> I don't think armv6 is a sufficiently common host for us to
>> worry too much about how its atomic primitives come out.
>> ARMv7 and 64-bit ARMv8 are more relevant, I think.
>> (v7 probably gets compiled the same way as v6 here, though.)
>
> Well, v6 is raspberry pi isn't it?

Yes, but v6 is also pretty slow anyhow, and if it wasn't
for the outlier raspi case then v6 would be definitely
irrelevant to everybody. Running QEMU on a slow ARM
board is unlikely to be a great experience regardless.
I'm not saying we should happily break v6, but I think
we're better off making optimisation decisions looking
forwards at v7 and v8 boards, rather than backwards at a
single legacy v6 board.

thanks
-- PMM