On Mon, Jan 24, 2022 at 08:40:36PM +0100, Mark Kettenis wrote: > > Date: Mon, 24 Jan 2022 20:19:46 +0100 > > From: Anton Lindqvist <an...@basename.se> > > > > On Mon, Jan 24, 2022 at 05:31:49PM +0100, Mark Kettenis wrote: > > > Currently we attach ACPI devices that are present in a machine. > > > However, in some cases ACPI devices can be present, but not enabled. > > > Attaching a device driver to devices that are not enabled is not a > > > good idea since reading and writing from/to its registers will fail > > > and the driver will malfunction in interesting ways. Such as a com(4) > > > serial port that is misdetected and hangs the kernel when it is > > > actually opened. > > > > > > The diff below makes sure we only enable devices that are actually > > > enabled. This may cause some devices to disappear in OpenBSD. > > > However those devices should have been unusable anyway, so that isn't > > > an issue. > > > > > > ok? > > > > According to the ACPI specification[1]: > > > > > A device can only decode its hardware resources if both bits 0 and 1 are > > > set. If the device is not present (bit [0] cleared) or not enabled (bit > > > [1] cleared), then the device must not decode its resources. > > Just before that it says: > > If bit [0] is cleared, then bit 1 must also be cleared (in other > words, a device that is not present cannot be enabled). > > > Should we therefore check for presence of both STA_PRESENT and > > STA_ENABLED? > > So according to the ACPI specification we don't need to do that. > Should we do it just to be safe?
I would still vote for it.
