On Thu, Sep 22, 2011 at 12:35:13AM -0400, Kevin O'Connor wrote:
On Wed, Sep 21, 2011 at 03:44:13PM +0300, Michael S. Tsirkin wrote:
The reason is that our acpi tables declare both _RMV with value 0, and _EJ0 method for these slots. What happens in this case is undocumented by ACPI spec, so linux ignores _RMV, and windows seems to ignore _EJ0.
Could the DSDT just not define _EJ0 for device 1 & 2 instead of dynamically patching them? (Would there ever be a case where we wouldn't know at compile time which devices need _EJ0?)
Yes. in qemu we can make any slot non hotpluggable on command line by requesting a non hotpluggable device be put there.
The correct way to suppress hotplug is not to have _EJ0, so this is what this patch does: it probes PIIX and modifies DSDT to match.
The code to generate basic SSDT code isn't that difficult (see build_ssdt and src/ssdt-proc.dsl). Is there a compelling reason to patch the DSDT versus just generating the necessary blocks in an SSDT?
-Kevin
I don't really care whether the code is in DSDT or SSDT, IMO there isn't much difference between build_ssdt and patching: main reason is build_ssdt uses offsets hardcoded to a specific binary (ssdt_proc and SD_OFFSET_* ) while I used a script to extract offsets.
I think we should avoid relying on copy-pasted binary because I see the related ASL code changing in the near future (with multifunction and bridge support among others).
I can generalize the approach though, so that it can work for finding arbitrary names without writing more scripts, hopefully with the potential to address the hard-coded offsets in acpi.c as well. Does that sound interesting?