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Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api |
Date: |
Thu, 21 May 2009 14:31:26 +0100 |
User-agent: |
KMail/1.11.2 (Linux/2.6.29-2-amd64; KDE/4.2.2; x86_64; ; ) |
On Thursday 21 May 2009, Paul Brook wrote:
> > > MSI provides multiple edge triggered interrupts, whereas traditional
> > > mode provides a single level triggered interrupt. My guess is most
> > > devices will want to treat these differently anyway.
> >
> > So, is qemu_send_msi better than qemu_set_irq.
>
> Neither. pci_send_msi, which is a trivial wrapper around stl_phys.
To clarify, you seem to be trying to fuse two largely separate features
together.
MSI is a standard PCI device capability[1] that involves the device performing
a 32-bit memory write when something interesting occurs. These writes may or
may not be directed at a APIC.
The x86 APIC has a memory mapped interface that allows generation of CPU
interrupts in response response to memory writes. These may or may not come
from an MSI capable PCI device.
Paul
[1] Note a *device* capability, not a bus capability.
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, (continued)
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api,
Paul Brook <=
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Michael S. Tsirkin, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Avi Kivity, 2009/05/21
- Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api, Paul Brook, 2009/05/21