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. > -- > /kashyap
