Re: [PATCH v2 3/5] MdeModulePkg: implement generic PCI I/O driver for non-discoverable devices

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 15 November 2016 at 11:30, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> On 15 November 2016 at 08:40, Ni, Ruiyu <ruiyu.ni@intel.com> wrote:
>> Ard,
>> Can you check whether PciLib can be used to replace the implementation in
>> NonDiscoverablePciDeviceIo.c?
>>
>
> OK

I am not sure how this should work. This driver needs to coexist with
real PCI host bridge drivers, and the config space access method is
fully defined by the requirements of the driver, i.e., each PCI config
space access should be served from the fake PCI config space in
memory, and never be forwarded to a real device.

So /providing/ a PciLib implementation, and requiring that that
particular implementation must be used with this driver makes no
sense, I think.
And depending on a PciLib implementation does not make sense either,
since the platform cannot choose which method to use.

Note that we are not emulating a PCI bus hierarchy, where a single
contiguous chunk of memory emulates the entire config space of several
devices. Each device is fully independent, and provides a minimal
config space to describe the type of device, and the BARs

Or did I miss something?