Re: [PATCH V1 11/11] arm64, pci, acpi: Support for ACPI based PCI hostbridge init

From: Arnd Bergmann
Date: Tue Nov 03 2015 - 11:01:04 EST

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.

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