On 08/05/17 23:38, Marvin H?user wrote:
> Dear developers,
>
> While browsing the KabylakeSiPkg code, I noticed that 64-bit registers are
> read directly via MmioRead64() as there is no PciRead64() function.
> Is there a specific reason there are no PciRead64() and PciExpressRead64()
> functions or were they simply not needed previously?
Validity of 64-bit accesses to PCI config space is platform dependent
[*] and I guess the PciLib designers didn't want to deviate from the
common interface pattern that PciReadXX() always succeeds (as long as
the input parameter is valid), regardless of XX.
[*] The UEFI spec repeats the following paragraph in several places:
The I/O operations are carried out exactly as requested. The caller
is responsible satisfying any alignment and I/O width restrictions
that the PCI controller on a platform might require. For example on
some platforms, width requests of EfiPciIoWidthUint64 do not work.
Thanks
Laszlo
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