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Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs |
Date: |
Sun, 13 Jun 2010 16:49:02 +0100 |
User-agent: |
KMail/1.13.3 (Linux/2.6.33-2-amd64; KDE/4.4.4; x86_64; ; ) |
> I think we could solve all problems (well, maybe not world peace, yet)
> by switching to message based system for all of DMA and IRQs.
>
> Each device would have a message input port and way to output messages.
>
> Examples:
>
> Zero copy memory access from device D1 to D2 to host memory (D3) with
> access broken to page length units and errors occurring on the last
> byte:
> D1 send_msg(ID, MSG_MEM_WRITE, DMA address, length) -> D2
>...
> IRQ delivery chain D1->D2->D3 with coalescing, messages, delivery
> reporting and EOI:
> D1 send_msg(ID, MSG_IRQ_RAISE, payload) -> D2
This feels like a terrible idea to me. It introduces an unnecessary RPC
indirection layer without actually solving any of the problems. It just makes
it harder (if not impossible) for the compiler to verify any of the interfaces
between objects.
If we need a mechanism for a device to query the state of its outgoing IRQ
lines (which is what I mentioned previously), then we can just add that. I
still maintain that qemu_irq is *not* a message passing interface, and that
this absence is a good thing. Maybe if I make the qemu_irq code actively
suppress redundant level change notices that would make things clearer.
Paul
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, (continued)
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Jan Kiszka, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/12
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs,
Paul Brook <=
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Paul Brook, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Blue Swirl, 2010/06/13
- Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs, Gleb Natapov, 2010/06/14
[Qemu-devel] [PATCH 10/16] x86: Refactor RTC IRQ coalescing workaround, Jan Kiszka, 2010/06/06