Dana H. Myers wrote: > Li, Aubrey wrote: >> Liu, Jiang wrote: >> >> >>> Hi all. >>> I have analyzed relative code with Aubrey, and could >>> only give one >>> possible explanation for the phenomenon. It may be caused by buggy >>> ACPI BIOS implementation which returns non Package object on _CST >>> evaluation, and current cpupm driver dosen't check whether the >>> returned object is a >>> package object before access it. So if a Integer object is returned, >>> obj->Package.Elements will be NULL, then #GP happens. >>> Otherwise I couldn't >>> explain why "cnt = obj->Package.Elements[0].Integer.Value;" cause >>> #GP. Thanks! >> >> Right, we need to use AcpiEvaluateObjectTyped to call _CST with >> ACPI_TYPE_PACKAGE if we run into this case. >> > Agreed; that occurred to me this morning, that we're not > checking the type of the returned object before accessing it, > or using AcpiEvaluateObjectTyped(). So, yes, this is a necessary > change, after we understand what it actually broken here. >> But who knows how BIOS implements _CST, I'm waiting for the DSL file. >> > So, now that I've had a chance to look at the ACPI BIOS from an M10, > the issue is more interesting. > > There's no _CST object in the disassembly; the Toshiba BIOS uses the > ASL 'Load' operator to dynamically load objects as part of the per-CPU > _OSC object evaluation, which is where, I'm certain, the _CST objects > are coming from. > > This makes inspecting the relevant BIOS code a little more difficult. > I suggest that we first insert a kernel printf to tell us what type of > object is > returned from AcpiEvaluateObject(), to research this. >> And again, I don't think this is ACPICA related. >> > Why, again, are you discounting this possibility? Is there some > evidence you've seen that I haven't? :-) We have an unusual case > here - few BIOSes load tables at run time in my experience. It's > not inconceivable there's an ACPI CA bug here. > > Dana
Hopefully my connection remembered to bring in their M9 today for me to borrow.... Sounds like we are zeroing in on the real issue. I will re-read the ACPI spec regarding _OSC object evaluation + types and go from there. Thank you! Bill
