[Qemu-discuss] QEMU etc/e820 and fw_cfg

[Gordan Bobic]

I need to pass a custom e820 map to a virtual machine for
troubleshooting purposes and working around IOMMU hardware
bugs.

I have found references to a custom map being providable
via an external file, mentioned as "etc/e820" and "fw_cfg".
Unfortunately, I have not found any documentation that
explains how to use this from userspace when invoking
qemu. Can anybody point me in the right direction?

What is the exact format of this e820 map file and how
do I tell qemu to use it (and where to find it) when
initializing the guest environment?

Many thanks.

Gordan