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Re: [Qemu-devel] [RFC] in-kernel irqchip : split devices


From: Avi Kivity
Subject: Re: [Qemu-devel] [RFC] in-kernel irqchip : split devices
Date: Sun, 25 Oct 2009 12:26:51 +0200
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On 10/14/2009 04:30 PM, Glauber Costa wrote:
Hello people,

As I promised, I am sending a very brief PoC wrt split devices and in-kernel 
irqchip.
In this mail, I am including only the ioapic version for apreciation. I also 
have i8259,
and apic will take me a little bit more. This is just to try to bind the 
discussion to real
code.


I still can't say I like it. The reset function is duplicated, the state representation (which is an ABI) is gratuitously forked.

You can't save/restore in-kernel irqchip and userspace irqchip, even though where the code is located is an implementation detail. While we may not care much for the ioapic, it sets a bad precedent for vhost-net, where we'd like to migrate from non-vhost-net hosts to vhost-net hosts without the user noticing anything.

Note that we end up with a very slim representation of the device, and the code 
is much less
confusing, IMHO.

You can always remove if statements by duplicating the code and pushing the if one level upwards. In total, there is more code, and it is more confusing (since you need to deal with implementation details at a higher level).

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





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