On Tuesday 03 November 2015 10:10:21 Sinan Kaya wrote:
I don't see anywhere in the SBSA spec addendum that the PCI configuration space section that unaligned accesses *MUST* be supported.
If this is required, please have this info added to the spec. I can work with the designers for the next chip.
Unaligned access on the current hardware returns incomplete values or can cause bus faults. The behavior is undefined.
Unaligned accesses are not allowed, but any PCI compliant device must support aligned 1, 2 or 4 byte accesses on its configuration space, though the byte-enable mechanism. In an ECAM host bridge, those are mapped to load/store accesses from the CPU with the respective width and natural alignment.
Arnd