[vbox-dev] MSI support with ICH9 chipset

Vilbig, Ric ric_vilbig at mentor.com
Thu Mar 31 14:20:12 UTC 2016


I recently asked if the ICH9 chipset must be used with virtual devices which require MSI interrupt support, and learned that yes it is required.  The PIIX3 chipset does not support MSI.  (see attached)

So I have migrated to a new VM that uses ICH9 chipset, but have found I still have the same MSI problem as with PIIX3.

When VBox or BIOS sets up the MSI structure in the extended PCI config space of my virtual device, it sets the address field to fee0100c (upper=0).  However, that does not appear to be within any mapped address range - the closest thing is APIC, in the range fee00000 to fee00fff.

So when my device tries to raise an interrupt by DMA writing to fee0100c, VBox cannot find an address range, so the write never actually happens.  Therefore no interrupt happens, so the device cannot work correctly.

Is there some other bit of VM configuration that I must do for MSI support?  I noticed in the logs that LAPIC is disabled, so I wonder if my VM is just missing something.

Log files are attached, pruned to meet the 100k email limit (original available upon request).  Lines bearing the "RicV" prefix were instrumented by me while troubleshooting.  Lines bearing the "RemDev" prefix are coming from my PDM plug-in.  I also inserted C-style comments at the point interesting points.

Environment: VBox 5.0.16 built from OSE tarball on the downloads page, running on Ubuntu 14 host, with Ubuntu 14 guest.


Ric Vilbig
Mentor Graphics, Emulation Division
46871 Bayside Parkway, Fremont CA, 94538
Phone:  510-354-7360
Mobile: 408-529-2365
email:  ric_vilbig at mentor.com<mailto:ric_vilbig at mentor.com>

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Subject: Re: [vbox-dev] Chipset support for Message Signaled Interrupts (MSI)
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