* Direct Device Assignment in Xen DomU.
@ 2014-08-12 6:54 manish jaggi
2014-08-12 9:27 ` Stefano Stabellini
0 siblings, 1 reply; 3+ messages in thread
From: manish jaggi @ 2014-08-12 6:54 UTC (permalink / raw)
To: xen-devel, Stefano Stabellini, Ian Campbell, Julien Grall, manish.jaggi
Hi,
On our platform there are 2 uarts. Is there a feature in Xen to assign
a uart to DomU.
As uart is not a bus master IOMMU is not required.
I couldnt find anything googling for this.
-Regards
Manish
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Direct Device Assignment in Xen DomU.
2014-08-12 6:54 Direct Device Assignment in Xen DomU manish jaggi
@ 2014-08-12 9:27 ` Stefano Stabellini
2014-08-13 8:13 ` manish jaggi
0 siblings, 1 reply; 3+ messages in thread
From: Stefano Stabellini @ 2014-08-12 9:27 UTC (permalink / raw)
To: manish jaggi
Cc: Julien Grall, xen-devel, manish.jaggi, Ian Campbell, Stefano Stabellini
On Tue, 12 Aug 2014, manish jaggi wrote:
> Hi,
>
> On our platform there are 2 uarts. Is there a feature in Xen to assign
> a uart to DomU.
> As uart is not a bus master IOMMU is not required.
>
> I couldnt find anything googling for this.
Today Xen cannot distinguish between bus mastering devices and non bus
mastering devices. Therefore without an IOMMU in front of it, Xen is
going to assume that it wouldn't be safe to assign the device to the
guest.
However Xen provide ways to remap generic mmio regions and interrupts
into a guest, so you could simply do that to get the uart in your domU.
Just add:
iomem=["0x10000,2"]
irqs=[109]
to your VM config file, where 109 is the uart irq, 0x100 the start mfn
and 2 the number of pages to remap. Give a look at man xl.cfg for more
info. You also need to take care of disabling the second uart in dom0
and/or Xen.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Direct Device Assignment in Xen DomU.
2014-08-12 9:27 ` Stefano Stabellini
@ 2014-08-13 8:13 ` manish jaggi
0 siblings, 0 replies; 3+ messages in thread
From: manish jaggi @ 2014-08-13 8:13 UTC (permalink / raw)
To: Stefano Stabellini; +Cc: Julien Grall, xen-devel, manish.jaggi, Ian Campbell
Thanks stefano for a quick reply
On 12 August 2014 14:57, Stefano Stabellini
<stefano.stabellini@eu.citrix.com> wrote:
> On Tue, 12 Aug 2014, manish jaggi wrote:
>> Hi,
>>
>> On our platform there are 2 uarts. Is there a feature in Xen to assign
>> a uart to DomU.
>> As uart is not a bus master IOMMU is not required.
>>
>> I couldnt find anything googling for this.
>
> Today Xen cannot distinguish between bus mastering devices and non bus
> mastering devices. Therefore without an IOMMU in front of it, Xen is
> going to assume that it wouldn't be safe to assign the device to the
> guest.
>
> However Xen provide ways to remap generic mmio regions and interrupts
> into a guest, so you could simply do that to get the uart in your domU.
> Just add:
>
> iomem=["0x10000,2"]
> irqs=[109]
>
> to your VM config file, where 109 is the uart irq, 0x100 the start mfn
> and 2 the number of pages to remap. Give a look at man xl.cfg for more
> info. You also need to take care of disabling the second uart in dom0
> and/or Xen.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-08-13 8:13 UTC | newest]
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2014-08-12 6:54 Direct Device Assignment in Xen DomU manish jaggi
2014-08-12 9:27 ` Stefano Stabellini
2014-08-13 8:13 ` manish jaggi
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