Re: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary
From: "Maciej W. Rozycki" <macro@orcam.me.uk>
Date: 2022-05-06 13:17:10
Also in:
linux-alpha, linux-arch, linux-arm-kernel, linux-m68k, linux-mips, linux-pci, linux-riscv, linux-sh, lkml, sparclinux
On Fri, 6 May 2022, Arnd Bergmann wrote:
quoted
So what happens if the instruction is given an I/O rather than memory BAR as the relevant argument? Is the address space indicator bit (bit #0) simply ignored or what?Not sure. My best guess is that it would actually work as you'd expect, but is deliberately left out of the architecture specification so they don't have to to validate the correctness. Note that only a small number of PCIe cards are actually supported by IBM, and I think the firmware only passes devices to the OS if they are whitelisted.
That makes sense, thanks! Maciej