On Thu, May 15, 2014 at 2:39 PM, Jan Kiszka <jan.kiszka@xxxxxx> 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. Arthur > > Jan > >> >> I have tried to disable IDE DMA in guest OS booting params as follows: >> ide-core.nodma=0.0 libata.dma=0 ide=nodma ide0=nodma >> >> But I can also get the followings in dmesg: >> [0.533276] ata1: PATA max MWDMA2 cmd 0x1f0 ctl 0x3f6 bmdma 0xc040 irq 14 >> [0.533641] ata2: PATA max MWDMA2 cmd 0x170 ctl 0x376 bmdma 0xc048 irq 15 >> >> and I do tracked irq 14 and irq 15 in ioapic_deliver when read/write disk. >> >> How could I totally disable IDE BMDMA from guest's boot time? >> >> Thanks, >> Arthur >> > > -- Arthur Chunqi Li Department of Computer Science School of EECS Peking University Beijing, China -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
