Finally got time to do some more poking around regarding this. I haven't read the entire ACPI spec, so bear with me...

As John Baldwin said, the wrapper nvidia_acpi.c passes in a buffer instead of a package. In the definition for _DSM, you can see calls to NVOP, NVPS, and NBCI. I looked at all three, and they seem to treat Arg3 as a buffer as well (they call CreateField on it, which according to the ACPI spec, should take a buffer argument).


So it looks like both the nvidia driver as well as the ALS code are pretty thoroughly convinced that Arg3 (the fourth arg) is a buffer instead of a package, despite what the spec says about what it "should" be.

Could this possibly be fixed by adding some kind of quirk to the ACPI execution engine that says "_DSM's fourth argument is a buffer"?

On 06/24/2014 20:51, Eric McCorkle wrote:

It looks like this is the definition:

                     Method (_DSM, 4, NotSerialized)  // _DSM:
Device-Specific Method
                     {
                         If (\CMPB (Arg0, Buffer (0x10)
                                 {
                                     /* 0000 */   0xF8, 0xD8, 0x86,
0xA4, 0xDA, 0x0B, 0x1B, 0x47,
                                     /* 0008 */   0xA7, 0x2B, 0x60,
0x42, 0xA6, 0xB5, 0xBE, 0xE0
                                 }))
                         {
                             Return (NVOP (Arg0, Arg1, Arg2, Arg3))
                         }

                         If (\CMPB (Arg0, Buffer (0x10)
                                 {
                                     /* 0000 */   0x01, 0x2D, 0x13,
0xA3, 0xDA, 0x8C, 0xBA, 0x49,
                                     /* 0008 */   0xA5, 0x2E, 0xBC,
0x9D, 0x46, 0xDF, 0x6B, 0x81
                                 }))
                         {
                             Return (NVPS (Arg0, Arg1, Arg2, Arg3))
                         }

                         If (\WIN8)
                         {
                             If (\CMPB (Arg0, Buffer (0x10)
                                     {
                                         /* 0000 */   0x75, 0x0B, 0xA5,
0xD4, 0xC7, 0x65, 0xF7, 0x46,
                                         /* 0008 */   0xBF, 0xB7, 0x41,
0x51, 0x4C, 0xEA, 0x02, 0x44
                                     }))
                             {
                                 Return (NBCI (Arg0, Arg1, Arg2, Arg3))
                             }
                         }

                         Return (Buffer (0x04)
                         {
                              0x01, 0x00, 0x00, 0x80
                         })
                     }

Not sure if that's helpful at all...

Ah, the nvidia driver calls _DSM and it has the bug.  In its
nvidia_acpi.c file
it uses a Buffer instead of a Package for the fourth argument to
_DSM.  OTOH, the
warning doesn't prevent the method from running, so the warning may be
harmless.
You can try contacting the nvidia folks to tell them about the warning
and point
out the bug in their _DSM wrapper in nvidia_acpi.c to see what they say.

Will do.  Is there a preferred point of contact?
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