[PATCH v2 1/4] conf: add xen specific feature: e820_host

Jim Fehlig jfehlig at suse.com
Tue Apr 14 22:05:21 UTC 2020


On 4/13/20 8:37 PM, Marek Marczykowski-Górecki wrote:
> e820_host is a Xen-specific option, only available for PV domains, that
> provides the domain a virtual e820 memory map based on the host one. It
> is required when using PCI passthrough and is generally considered safe
> for any PV kernel. e820_host is silently ignored if set in HVM domain
> configuration. See xl.cfg(5) man page in the Xen documentation for more
> details.
> 
> Signed-off-by: Marek Marczykowski-Górecki <marmarek at invisiblethingslab.com>

This looks good to me now so

Reviewed-by: Jim Fehlig <jfehlig at suse.com>

But before pushing I'd like to settle on mapping the new 'passthrough' xl.cfg 
option to libvirt. See 
https://www.redhat.com/archives/libvir-list/2020-April/msg00696.html

On xen 4.13 it seems 'passthrough' is enough for PV domains. Enabling it, and 
not e820_host, allows me to successfully hotplug a PCI device after PV domain 
creation. I haven't checked but I assume e820_host was needed to hotplug PCI 
devices with xen < 4.13?

Regards,
Jim





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