q35 is the newer one with better support for more CPUs, PCI-E vs PCI,
integrated SATA vs integrated IDE emulation, IOMMU emulation, and I
*think* it is needed for hotplugging CPUs/memory.

I thought we were supposed to use it because of the PCI-E part,
specifically.


On 12/27/18 3:18 PM, Brett Foster wrote:
> Why use q35? I always thought that wasn't recommended. At least a couple 
> years ago, that was my impression.
>
>
> Sent from my BlackBerry - the most secure mobile device
>
>   Original Message  
> From: erra...@yourstruly.sx
> Sent: December 27, 2018 12:12 PM
> To: fost...@edgeandvertex.org; b...@spamcop.net
> Cc: vfio-users@redhat.com
> Subject: Re: [vfio-users] Installing Catalyst prevents VM from booting.
>
>
> BTW I think the specific reason you want to separate your pcie endpoints on 
> q35 from the root complex using a switch or up/downstream ports is due to the 
> fact that the root complex has direct access to memory. I can't find anything 
> more specific regarding why that might be problematic but I know that pcie 
> addressing is different for devices downstream as opposed to being connected 
> directly to the root complex. I arrived at the conclusion that the amd driver 
> works now with q35 because changed the topology as per the advice I read 
> somewhere regarding how it should be done. I'd like to know for sure but I 
> don't really understand PCIe well enough and I think as far as the driver is 
> concerned its up to a guess as to why one configuration works and the other 
> doesn't (unless you have better luck getting the windows remote kernel 
> debugging to work than I have.)
> ________________________________________
> From: vfio-users-boun...@redhat.com <vfio-users-boun...@redhat.com> on behalf 
> of Brett Foster <fost...@edgeandvertex.org>
> Sent: Wednesday, December 26, 2018 11:24:48 AM
> To: Bronek Kozicki
> Cc: vfio-users
> Subject: Re: [vfio-users] Installing Catalyst prevents VM from booting.
>
> I have been using AMD via i440fx for like 5 years or so (across different 
> hardware and graphics cards). The drivers that work are the ones that come 
> via Windows Update. The drivers distributed by AMD do not. Not sure why since 
> presumably they come from the same place. lol.
>
> On Tue, Dec 25, 2018 at 9:51 AM Bronek Kozicki 
> <b...@spamcop.net<mailto:b...@spamcop.net>> wrote:
> On Tue, 25 Dec 2018, at 4:21 PM, Paige Thompson wrote:
>> Hey,
>>
>> From what I understand in general connecting devices straight to the
>> root complex is problematic and they should be connected to a bridge. I
>> was kind of wondering if anybody had any knowledge of this. I find the
>> configuration really confusing. I still cant really tell how the
>> topology works.
>
> Hope Alex will shed some light on it when he's back from the holiday break.
>
>
> --
>   Bronek Kozicki
>   b...@spamcop.net<mailto:b...@spamcop.net>
>
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