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From: | Alexander Graf |
Subject: | Re: [Qemu-devel] [PATCH 5/7] hw/core/sysbus: add fdt_add_node method |
Date: | Thu, 24 Jul 2014 01:02:29 +0200 |
User-agent: | Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
On 23.07.14 17:33, Eric Auger wrote:
On 07/08/2014 03:52 PM, Alexander Graf wrote:On 07.07.14 09:08, Eric Auger wrote:This method is meant to be called on sysbus device dynamic instantiation (-device option). Devices that support this kind of instantiation must implement this method. Signed-off-by: Eric Auger <address@hidden>For the reason I stated earlier, I don't think it's a good idea to put device tree code into our device models.Hi Alex, I would propose we discuss that topic during next KVM call if you are available.
I lost track when that would be. Next week would work fine, the week after not :).
Hope Peter will be available to join too. Because I feel stuck between not putting things in the machine file (1) - obviously we could put them in a helper module (2) - and not putting them in the device (3). Whatever the solution I fear we are going to pollute something: Any time a new device wants to support dynamic instantiation, we would need to modify the machine file or the helper module with 1 and 2 resp. In case we put it in the device we pollute this latter... My hope was that quite few QEMU platform devices would need to support that feature and hence would need to implement this dt node generation method. To me dynamic instantiation of platform device was not the mainstream solution.
Quite frankly I don't think it'd be that many. I think we'll cover 99.9% of all use cases if we just enable it for the virt machines of e500 and arm.
Then there is the fundamental question of technical feasibility of devising a generic PlatformParams that match all the specialization needs? Here I miss experience. In case we know the machine type and a small set of additional fields couldn't we do the adaptations you talked about, related to IRQs?
The problem is that I don't know all the boards and different things people come up with either. There's also no reason machine files have to stick to the "platform bus" model - they could just take those devices and stick them into an existing other virtual bus.
I don't feel comfortable generalizing something where I'm pretty sure things will blow up sooner or later.
Alex
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