From what I've seen, the BMC would interact with a CXL using MCTP and not PCIe. See https://www.dmtf.org/sites/default/files/standards/documents/DSP0281_1.0.0_0.pdf
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Patrick Williams

> On May 9, 2024, at 4:58 PM, Ananth, Rajesh <rajesh.ananth@smartm.com> wrote:
> 
> 
> Hi,
>  
> We are in the process of developing OpenBMC based firmware update mechanism for the PCI-e based CXL controllers. The CXL controllers typically expose their interfaces as a memory mapped mailbox in the PCI-e space.
>  
> Basic things we are looking forward to implement are (depends on the feasibility here):
> 1.       Probe the PCI-e config space to locate our controller  (using PCI VID/DID)
> 2.       Probe the PCI-e config space to access the memory mapped registers
> 3.       Use the mapped registers to send commands and update the firmware
>  
> We would like to have some pointers on how to proceed (sample code/development docs etc.,). We are initially targeting s2600wf board as our target.
>  
> Thanks,
> Rajesh
>  
>