Bartosz, Based on your findings, the AddrRangeMin has to be a device address☺
As far as I can remember, this history is: In the very beginning, Spec owner assumes the device address equals to CPU address. The implementation of GetBarAttributes() directly returns the address read from the BAR. But later we found device address doesn’t equal to CPU address, especially in ARM platform. So in order to expose the offset of the two addresses, the AddressTranslationOffset field was used. To avoid breaking the existing consumers, GetBarAttributes() remains to return the BAR address. Anyone please correct me if I am wrong. Thanks, Ray From: Bartosz Szczepanek [mailto:[email protected]] Sent: Monday, September 4, 2017 7:43 PM To: [email protected] Cc: Ni, Ruiyu <[email protected]> Subject: [edk2] CPU/PCI addressing in PciIoGetAttributes Hi guys, I have some doubt about PciIoGetAttributes behaviour on aarch64 platform with non-uniform CPU:PCI address space mapping. I'll be grateful if you verify my understanding. According to UEFI specification, AddrRangeMin in QWORD Address Space Descriptor returned by PciIoGetAttributes() should be a CPU address, at least that's what I conclude from: > Address Translation Offset. Offset to apply to the Starting address of a > BAR *to convert it to a PCI address*. This value is zero unless the > HostAddress and DeviceAddress for the BAR are different. This mentions "Starting address", which I suppose refers to AddrRangeMin. It needs to be converted to PCI address, so as-is it should be in CPU address space. On the other hand, the AddrRangeMin is assigned BaseAddress value obtained directly from PciBar: > Descriptor->AddrRangeMin = PciIoDevice->PciBar[BarIndex].BaseAddress; PciBar is filled in PciParseBar() using original BAR content (thus BaseAddress is not translated, PCI address). This way value that refers to PCI space is returned from PciIoGetBarAttributes as CPU address. Shouldn't there be translation of it somewhere on the way? Or is my understanding flawed? Either way, please let me know. Best regards, Bartosz _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
