Right, I know what is causing this now. We have a complex interaction of
three things:
1. Early EC initialisation introduced by commit
c04209a7948b95e8c52084e8595e74e9428653d3
2. Timing (especially on multiprocessor / multitasking systems)
3. Possible 'problem' with ACPI DSDT embedded controller logic
When the EC is initialised before the rest of the ACPI namespace, any
references in the EC _REG() method to other node names will fail since
they're not yet known. In the case of the PCs being affected by this
bug, there is a Notify(BAT0, 0x81) or similar. BAT0 is not yet known but
the notify causes a general purpose event (GPE) to be fired which goes
unhandled and times out.
When boot option "quiet" is enabled there are very few kernel messages
being logged so everything executes faster. When "quiet" is removed, or
debugging of any kind is enabled, the additional time taken to log
messages gives enough breathing space for the ACPI namespace to be
scanned and the other objects created before the timeout occurs.
The _REG(RegionSpace, 1) control method is used to notify AML that an
operation region is available. It is not clear from the ACPI
specification whether _REG() is allowed to Notify() other nodes. If the
namespace is fully scanned it shouldn't be an issue, but when the EC is
started early via an ECDT or by virtue of the commit here (intended to
provide the ECDT equivalent for BIOSes without it), then it can cause a
failure.
I edited the EC's _REG() method and disabled the Notify(BAT0...) call and then
installed the revised DSDT in an initrd image. I kept the original initrd with
a different name and added an additional boot entry into the GRUB menu. I then
tested both initrd images. The one containing the modified DSDT with Notify()
disabled starts correctly. The original DSDT causes it to fail.
$ sudo acpidump -b -t DSDT -o DSDT.aml
$ iasl -d DSDT.aml
$ gedit DSDT.dsl
Device (EC)
...
Method (_REG, 2, NotSerialized)
{
If (LEqual (Arg0, 0x03))
{
Store (Arg1, ECON)
Store (BATP, BNUM)
Store (RSCL, B0SC)
Store (RPWR, PWRS)
/* Notify (BAT0, 0x81) not allowed for early-init ECs
*/
PNOT ()
If (LEqual (PRCP, One))
{
Notify (DOCK, Zero)
}
If (LEqual (WKSR, 0x02))
{
Notify (DOCK, One)
}
}
}
I rebuilt the DSDT:
$ iasl DSDT.dsl
$ sudo cp DSDT.aml /etc/initramfs-tools/
$ sudo mv /boot/initrd.img-2.6.24-16-generic
/boot/initrd.img-2.6.24-16-generic-ec-bug
$ sudo update-initramfs -u ALL
$ sudo mv /boot/initrd.img-2.6.24-16-generic
/boot/initrd.img-2.6.24-16-generic-ec-fix
Now edit /boot/grub/menu.lst, edit the initrd name and add another menu
option:
title Ubuntu Hardy 64-bit, kernel 2.6.24-16-generic EC fix
root (hd0,4)
kernel /vmlinuz-2.6.24-16-generic
root=UUID=bb2c3a14-1588-4fb9-8411-71f114b568b4 ro quiet
initrd /initrd.img-2.6.24-16-generic-ec-fix
quiet
title Ubuntu Hardy 64-bit, kernel 2.6.24-16-generic EC bug
root (hd0,4)
kernel /vmlinuz-2.6.24-16-generic
root=UUID=bb2c3a14-1588-4fb9-8411-71f114b568b4 ro quiet
initrd /initrd.img-2.6.24-16-generic-ec-bug
quiet
------
I have a large collection of DSDTs from across the Vaio range as part of
my SNC research. I ran an analysis script on them all to see how many
have a Notify() call in the EC _REG() control method (listed as model-
BIOS_version):
VGN-AR31S-R0200J6, VGN-AR370E-R0200J6, VGN-C140G-R0030J4, VGN-C1S, VGN-
C1ZB-R0034J4, VGN-C22GH-R0080J4, VGN-C240E-R0080J4, VGN-C2S-R0080J4,
VGN-C2Z-R0080J4, VGN-FE11H-R0072J3, VGN-FE11H-R0074J3, VGN-FE11M-
R0172J3, VGN-FE11M-R0174J3, VGN-FE21H-R0100J3, VGN-FE21M-R0130J3, VGN-
FE31M, VGN-FE31M-R0170J3, VGN-FE41E-R0190J3, VGN-FE41M-R0190J3, VGN-
FE41Z-R0200J3, VGN-FE45G-R0190J3, VGN-FE550G-R0074J3, VGN-FE590P-
R0072J3, VGN-FE660G-R0133J3, VGN-FE670G-R0130J3, VGN-FE690-R0172J3, VGN-
FE770G-R0173J3, VGN-FE830, VGN-FE870E-R0190J3, VGN-FE880EH-R0200J3, VGN-
FS115M-R0104J0, VGN-FS215B-R0040J1, VGN-FS215E-R0040J1, VGN-FS285H-
R0040J1, VGN-FS315E-R0084J1, VGN-FS315H-R0080J1, VGN-FS315S-R0084J1,
VGN-FS660W-R0044J1, VGN-FS730W-R0080J1, VGN-FS740W-R0080J1, VGN-FS760W-
R0080J1, VGN-FS965F-R0044J2, VGN-FS980-R0044J2, VGN-FZ11M-R0050J7, VGN-
N130G-R0020J4, VGN-N230E-R0070J4, VGN-N31Z-R0100J4
This issue could end up impacting a *lot* of users not just of Vaios but
other brands too. I've seen at least 3 others mentioned in bug reports
in the kernel.org bugzilla. What is worrying is that the kernel ACPI
guys seem to be sticking with the early EC initialisation and telling
users to create a custom DSDT.
--
[Hardy] ACPI Embedded Controller (EC) stops boot when kernel boot 'quiet'
option is enabled
https://bugs.launchpad.net/bugs/191137
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