Comment 1 for bug 1918917
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| Arnd Bergmann (arnd-arndb) wrote Re: synchronous about on accessing unused I/O ports on aarch64 | #1 |
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0f7b58d
(Get the code!)
My best guess is that the PCI I/O port handling in qemu only returns data for ports that are connected to an actual device.
In this case, the kernel attempts to access a 8250 serial port at an address where none exists. While this is also a bug in the kernel, a real PCI implementation would not cause an external abort but simply return 'all-ones' (0xff, 0xffff, 0xffffffff) for a read request and ignore writes. This is something that the kernel relies on for probing unknown ISA style devices.