[Bug]: mp tables bus ids

[adriangrigore]

Version

trunk/main

Host OS Type

all

Host OS name + version

any

Host Architecture

x86

Guest OS Type

all

Guest Architecture

x86

Guest OS name + version

No response

Component

Other

What happened?

ISA bus id is 0 in the mp tables and PCI bus id is 1 in the mp tables, however the default pci bus is 0. This leads to problems when reading interrupt redirects from the mp tables, as PCI redirects (busno 0) may be read from the ISA mp redirect table (busid also 0). Qemu solves this in the mp tables by having 0 as the pci bus id and 1 as the isa bus id.

Place where I assume mp tables bus ids are set https://github.com/VirtualBox/virtualbox/blob/main/src/VBox/Devices/PC/DevFwCommon.cpp#L1168

Not sure if this would break current virtual machines or it has to be kept for backwards compatibility.

How can we reproduce this?

Just boot any the machine...

Did you upload all of your necessary log files, screenshots, etc.?

• Yes, I've uploaded all pertinent files to this issue.