On Fri, Apr 18, 2014 at 06:43:25PM +0300, Paul Irofti wrote:
> This is the important part of the trace:
>
> > 4e10 Store
> > 4e11 \\_SB_.PCI0.LPCB.H_EC.CTMP
> > locking
> > field: aml_rwgas bitpos 1536 bpos 0 blen 8,flags 0x11
> > read 03 000000c0 0008 [\\_SB_.PCI0.LPCB.H_EC.ECR_]
> > gasio rd: 3 0xc0 1 1 851728760
> > aml_bufcpy: 0x90
> > unlocking
> > 4e28 Local0
> > 4e29 If
> > 4e2b LNotEqual
> > 4e2d Local0
> > 4e2e 0xff
> > 4e30 Return
> > 4e31 Add
> > 4e32 0x0aac
> > 4e35 Multiply
> > 4e36 Local0
> > 4e37 0x0a
> > acpitz0: critical temperature exceeded 144C, shutting down
>
> What happens is that we read 8 bits from bit-position (bitpos) 1536
> from the ECR field from the EC and then store it in Local0.
>
> What we read from there is 0x90, which is 144 in decimal.
>
> The revelant AML code looks like this:
>
> Store (\_SB.PCI0.LPCB.H_EC.CTMP, Local0)
> If (LNotEqual (Local0, 0xFF))
> Return (Add (0x0AAC, Multiply (Local0, 0x0A)))
>
> CTMP is supposed to keep the temperature in Celsius, thus it needs a
> conversion to Kelvin.
>
> So what this does is check if the value it just read is different from
> 0xFF and if so it converts the value to Kelvin degrees and returns them
> to the upper layers as required by the ACPI spec.
>
> Local0 * 10 + 2732 => 4172 which is 417.2K as dictated by the spec.
>
> Then userland transforms it back to Celsius and freaks out.
>
>
> The field, from your AML dump, looks like the following:
>
> Field (ECR, ByteAcc, Lock, Preserve) {
> [...]
> Offset (0xC0),
> CTMP, 8,
> [...] }
>
> Offset 0xC0 is the offset in bytes from the beginning of the field and
> it's 192 in decimal which translates to 192 * 4 = 1536 bits.
> This matches the bitpos from which the temperature was read, so the
> position is correct.
>
> Thus the bad news is that the bug is not a bitpos parsing bug...
>
> This happens only with OpenBSD? Linux or Windows runs fine, right?
Both Windows and Linux run fine. I can not test Windows anymore but I
just started Fedora 20 and verified that the two thermal zones present
temperatur values that make sense.
