On Thu, Jun 06, 2019 at 06:19:43PM +0200, Kashyap Chamarthy wrote:
Hi folks,
Today I learnt about some obscure PCIe-related properties, in context of
the adding PCIe root ports to a guest, namely:
io-reserve
mem-reserve
bus-reserve
pref32-reserve
pref64-reserve
Unfortunately, the commit[*] that added them provided no documentation
whatsover.
In my scenario, I was specifically wondering about what does
"io-reserve" mean, in what context to use it, etc. (But documentation
about other properties is also welcome.)
Anyone more well-versed in this area care to shed some light?
[*] 6755e618d0 (hw/pci: add PCI resource reserve capability to legacy
PCI bridge, 2018-08-21)
So normally bios would reserve just enough io space to satisfy all
devices behind a bridge. What if you intend to hotplug more devices?
These properties allow you to ask bios to reserve extra space.