Re: [vfio-users] vfio-users Digest, Vol 32, Issue 3

[Alex Williamson]

On Sat, 10 Mar 2018 22:17:33 +
"Patrick O'Callaghan"  wrote:

> On Sat, 2018-03-10 at 18:40 +, Steve Glaser wrote:
> > Max Payload Size determines both what a Function can send and what a 
> > Function accepts. As such, it is almost always set to the lowest common 
> > denominator of everything in the PCIe Hierarchy.  
> ...
> 
> 
> Don't reply to digests. Even if you fix the subject line the threading
> will still be screwed up. Some mail clients (e.g. Evolution) allow you
> to reply to a specific message *within* a digest and avoid this
> problem. Otherwise, it's just better not to use digests at all. They
> are a remnant from the days of UUCP and don't convey any advantage in
> modern systems.
> 

OTOH, I'd rather see a mangled, informative reply from a digest user
than none at all.  Thanks,

Alex

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Re: [vfio-users] vfio-users Digest, Vol 32, Issue 3

[Patrick O'Callaghan]

On Sat, 2018-03-10 at 18:40 +, Steve Glaser wrote:
> Max Payload Size determines both what a Function can send and what a Function 
> accepts. As such, it is almost always set to the lowest common denominator of 
> everything in the PCIe Hierarchy.
...


Don't reply to digests. Even if you fix the subject line the threading
will still be screwed up. Some mail clients (e.g. Evolution) allow you
to reply to a specific message *within* a digest and avoid this
problem. Otherwise, it's just better not to use digests at all. They
are a remnant from the days of UUCP and don't convey any advantage in
modern systems.


poc

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Re: [vfio-users] vfio-users Digest, Vol 32, Issue 3

[Steve Glaser]

Max Payload Size determines both what a Function can send and what a Function 
accepts. As such, it is almost always set to the lowest common denominator of 
everything in the PCIe Hierarchy.

If there are Hot Plug slots, software might assume something about what might 
be added in those when determining the lowest common denominator. 

VFs don’t have their own setting. They use the PF value. The hypervisor 
emulates that field. 

Steveg

> On Mar 10, 2018, at 9:00 AM, "vfio-users-requ...@redhat.com" 
>  wrote:
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> Today's Topics:
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>   1. VFIO 128 byte TLP size? (Oliver Heid)
> 
> 
> --
> 
> Message: 1
> Date: Fri, 9 Mar 2018 18:03:14 +0100
> From: Oliver Heid 
> To: vfio-users@redhat.com
> Subject: [vfio-users] VFIO 128 byte TLP size?
> Message-ID: 
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> Does VFIO somehow limit PCIe TLP size to 128 bytes on virtualized 
> devices? In our case MaxPayload = MaxReadReq = 256 bytes in PCI config, 
> and we use 4k aligned base addresses and do not cross 4k boundaries, but 
> actual package size is only 128B. Any idea how to get 256 byte TLPs?
> Thanks!
> 
> 
> 
> --
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> End of vfio-users Digest, Vol 32, Issue 3
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