Re: [PATCH v3 19/35] x86/io_apic: Cleanup trigger/polarity helpers

[Paolo Bonzini]

On 10/11/20 09:59, David Woodhouse wrote:
> Hm, attempting to reproduce this shows something else. Ever since
> commit be62dbf554c5 ("iommu/amd: Convert AMD iommu driver to the dma-
> iommu api") in 5.5 the following stops working for me:
>
> $ qemu-system-x86_64 -serial mon:stdio -kernel bzImage  -machine q35,accel=kvm,kernel-irqchip=split -m 2G -device amd-iommu,intremap=off -append "console=ttyS0 apic=verbose debug" -display none
>
> It hasn't got a hard drive but I can watch the SATA interrupts fail as
> it probes the CD-ROM:
>
> [    7.403327] ata3.00: qc timeout (cmd 0xa1)
> [    7.405980] ata3.00: failed to IDENTIFY (I/O error, err_mask=0x4)
>
> Adding 'iommu=off' to the kernel command line makes it work again, in
> that it correctly panics at the lack of a root file system, quickly.

That might well be a QEMU bug though, AMD emulation is kinda experimental.

Paolo