On 2014-05-15 08:55, Arthur Chunqi Li wrote: > On Thu, May 15, 2014 at 2:39 PM, Jan Kiszka <jan.kis...@web.de> wrote: >> On 2014-05-15 07:54, Arthur Chunqi Li wrote: >>> Hi Jan and there, >>> >>> I want to disable IDE BMDMA in Qemu/KVM and let guest OS uses only PIO >>> mode. Are there any configurations in Qemu or KVM to disable the >>> hardware support of DMA? >> >> Not that I know. These features are built into the chipsets we emulate, >> and there seems to be no option to disable them. Maybe the isapc will >> not expose DMA capabilities - but will also lack a lot of other things >> like PCI... > > Well, if I boot guest Linux with ide-core.nodma=0.0 libata.dma=0 > ide=nodma ide0=nodma, why are bmdma irqs (14 and 15) also triggered? I > think guest OS should only use PIO in this situation.
To signal data availability e.g.? It's up to the guest driver if it makes use of asynchronous notifications or polls for this. Jan
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