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SubjectRe: Doubt on first access for PCIe device
On 04/11/2017 10:15 AM, abhijit wrote:

> Here I am assuming, the completer ID will be device number and function
> number that will eventually programmed in to device. In that case, my
> question is, without first write, how read request(VENDOR ID read) is
> serviced/routed?

You'll want to read about PCIe enumeration at boot time and how the BIOS
walks the topology to assign these (which an OS may later re-number). In
particular, read about ECAM for configuration. This uses memory mapped
config space read/write accessors that target a memory address space
under the control of the root complex.

Jon.

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