Re: [Qemu-devel] [PATCH v2] arm: add fw_cfg to "virt" board

[Peter Maydell]

On 9 December 2014 at 15:41, Laszlo Ersek <address@hidden> wrote:
> Again, this was the idea that Rich had in 2010 (see the links in the
> discussion thus far). It was rejected back then (which is why I didn't
> even try to resurrect it now), and Peter has now asked if anything has
> changed that would make that approach more acceptable now.
>
> "Avi and Gleb not hanging around so they can't block the approach now"
> might or might not be such a change; I don't know. But, I tend to trust
> their opinion, even if dates back to 2010 in this case.

Yeah, this is about my point of view. A direct-write-to-memory
fw_cfg doesn't seem too unreasonable to me, but it would be nice
to see a solidly argued case from its proponents to counterbalance
the previous rejection.

> Anyway I'm certainly not opposed to performance, so if someone can
> thoroughly refute everything they said in that thread, go ahead.

As far as I can tell the main line of argument was "if you're
using fw_cfg to transfer huge amounts of data you're doing
something wrong".

Is ARM much higher overhead than x86 for these accesses?

(Added Alex on cc as one of the few people from the previous
round of argument who's still active...)

-- PMM