Re: arm64 syzbot instances
From: Peter Maydell <hidden>
Date: 2021-03-20 20:44:27
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On Fri, 12 Mar 2021 at 09:16, Arnd Bergmann [off-list ref] wrote:
So it's probably qemu that triggers the 'synchronous external abort' when accessing the PCI I/O space, which in turn hints towards a bug in qemu. Presumably it only returns data from I/O ports that are actually mapped to a device when real hardware is supposed to return 0xffffffff when reading from unused I/O ports.
Do you have a reference to the bit of the PCI spec that mandates this -1/discard behaviour for attempted access to places where there isn't actually a PCI device mapped ? The spec is pretty long and hard to read... (Knowing to what extent this behaviour is mandatory for all PCI systems/host controllers vs just "it would be nice if the gpex host controller worked this way" would help in figuring out where in QEMU to change.) thanks -- PMM _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel