MCTP over PCI on AST2500
Thomaiyar, Richard Marian
richard.marian.thomaiyar at linux.intel.com
Wed Jan 15 02:54:16 AEDT 2020
Yes Jeremy. We are aware about the limitation, but as Sharad stated, we
will be starting with D-Bus based approach, due to priority ( and then
move to socket based approach, at-least not immediately).
Having said that pushed a WIP document for both MCTP & PLDM (still in
high level, and low level implementation details capturing are in
progress). We can further discuss in the review (for better tracking).
Note: Proposal is to have a abstraction layer between D-Bus & Socket, so
that upper layers like PLDM can switch to socket-driver based approach
at later stage.
Related to MCTP over PCIe Iowna will send out a review which will be
along the MCTP base design document.
On 1/14/2020 12:09 PM, Khetan, Sharad wrote:
> Thanks for the pointer Jeremy. We will look into demux daemon.
> On Jan 13, 2020, at 10:21 PM, Jeremy Kerr <jk at ozlabs.org
> <mailto:jk at ozlabs.org>> wrote:
>> Hi Ketan,
>> Just a suggestion - you probably don't want to be passing MCTP
>> messages over dbus - this is something we learnt from the IPMI
>> The current design of the mctp-demux-daemon (included in the libmctp
>> codebase) is intended to provide an interface that will be easy to
>> migrate to a future kernel implementation (ie., using sockets to pass
>> MCTP messages), and allows multiple applications to be listening for
>> MCTP messages of different types.
>> On 14 January 2020 1:54:49 pm AWST, "Khetan, Sharad"
>> <sharad.khetan at intel.com <mailto:sharad.khetan at intel.com>> wrote:
>> Hi Deepak,
>> On 13/01/20 10:23 PM, Khetan, Sharad wrote:
>> Hi Andrew, On Thu, 9 Jan 2020, at 12:27, Andrew Jeffery wrote:
>> On Sat, 21 Dec 2019, at 10:45, Khetan, Sharad wrote:
>> Hi Andrew, Sorry for late response. The plan is to
>> have MCTP in user space.
>> How are you handling this then? mmap()'ing the BAR from
>> Sorry, let me put my brain back in, I was thinking of the
>> wrong side of the BMC/Host MCTP channel. How much were
>> you planning to do in userspace on the BMC? As in, are
>> you planning to drive the BMC's PCIe MCTP controller from
>> userspace (presumably via /dev/mem)?
>> For implementation on the BMC, we agree that it's better to
>> do it in kernel (and as you mentioned - use consistent
>> interface to upper layers, provide another transport).
>> However, given the time needed to implement things in kernel
>> (and the review after), we are starting with a short term
>> solution. We will be implementing MCTP (protocol elements) in
>> user space, along with a low level MCTP PCIe driver just to
>> push bits on PCIe. Iwona is working on this and should be
>> able to describe the exact primitive.
>> Do you plan to do the user-space work as an extension to/reusing components from openbmc/libmctp?
>> Yes we plan to reuse and extend the libmctp, support PCIe as well as SMBus bindings. We plan to use d-bus extensions to existing libmctp. That said, we will know the exact extent of reuse/modifications when we really start implementing.
>> We are implementing this for AST 2600 (will not support any workarounds for AST 2500 bug).
>> @Andrew, Thanks for your response.
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