Hi luc1d,
The HCL primarily lists devices that will work with ESXi itself – i.e. you can use the device to attach the ESXi host to a storage device, a network, and so forth, using drivers that are supported on ESXi itself.
DirectPath I/O has a different set of requirements, in some ways more strict (limitations on what the device can actually do at the hardware level) and in some ways less strict (no need for ESXi drivers). Motherboard/builtin devices (and particularly chipset devices/functions) are particularly difficult to pass through to a guest, since the hardware/firmware/drivers may operate on the assumption that the whole chipset is under the control of one OS – not an unreasonable assumption in the real world.
I don't have a ready link to the DirectPath I/O device compatibility list... it is much shorter than the full HCL.
Cheers,
--
Darius