[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Adding new custom devices to Xen via QEMU



Thanks David,

This could very well be the issue, but could you please elaborate?
The questions that come up are the following:
What is the physical address range given to RAM? What range of addresses would work for my device?
And, if this is the case, how would I unpopulate the RAM?

There are reasons for the address chosen, and it works on other hypervisors (e.g. KVM) so although it might be easiest to change the address I really don't want to unless its the only way to keep from a Xen modification entirely.

Jason

On 9/30/2016 9:53 AM, David Vrabel wrote:
On 30/09/16 14:35, Jason Dickens wrote:
Hi Wei,

Thanks for the response. It make sense to me that if the device were on
the PCI bus (or other such bus, e.g. USB) that it could be discovered,
at least by an OS. Its something to consider. I should mention that our
guest VM doesn't actually use an OS.

However, the device is not implemented that as PCI it is simply memory
mapped. Technically, in QEMU is has type ISA because it was derived as a
modification of the TPM device. Is it possible something is lacking in
the QEMU model that Xen needs but KVM doesn't?
If the answer is that Xen should not need modification for any new
devices then this gives me hope.  You've also inspired some things to
try, like whether or not smaller modifications to the TPM device work.
One change that is significant to mention is that the physical address
range use is anomalous, by which I mean it not in the normal device range.
Does device MMIO overlap with guest RAM?  If so, you'll need to
unpopulate the RAM first.

David



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.