Re: upstream PowerPC qemu breakage

[Avi Kivity <avi@qumranet.com>]

Hollis Blanchard wrote:
> Hi Avi, we're having a problem with the qemu merge you just did in
> kvm-userspace.
>
> Upstream qemu recently added the TCG code generator to phase out dyngen.
> When he did that, Fabrice explicitly broke the build every non-x86
> architecture, and since you've now pulled that breakage into KVM, we're
> stuck in an awkward situation.
>
> In the short term we'll have to fork a working userspace, since we're in
> the middle of some other stuff (such as real guest IO, which I think is
> pretty important :) .
>   

I meant to drop Xiantao and you a note about this, but qemu merges tend 
to erase short-term memory.  I figured that since tcg is not used when 
using kvm, you could just stub it out.  The downside is that -no-kvm 
breaks, but we can live with that.


> Long term, one option is to try to define a new qemu target that
> completely bypasses the code generation parts of qemu. Anthony did that
> for x86 once, but there are at least a couple sticking points; not sure
> how long it will take. This is probably the best long-term way to avoid
> this situation in the future.
>   

It kills -no-kvm, which is a powerful debugging aid.

> Another long-term option is to fix TCG for PowerPC upstream, and I'm
> afraid that isn't feasible.
>   

I saw some talk that dyngen and tcg can coexist; but apparently that's 
not the case.  Hopefully qemu upstream will unbreak the damage.

> I guess merging with qemu while it's in a period of massive change
> wasn't the most opportune moment. Were there some device model changes
> you were eager to pick up?
>   

The e1000 patch for one; also doing regular small merges is much easier 
than irregular large ones.

-- 
error compiling committee.c: too many arguments to function


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