RE: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

RE: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Moore, Robert]

I must agree that this is a really bad idea.  Once we start allowing these
kinds of errors to slip by, there is potentially no end to it.  It's a very
slippery slope that will potentially plunge everyone into the same kind of
BIOS abyss that ACPI was intended to solve in the first place.

Worse, there are situations where the AML interpreter cannot "guess" what
the ASL/AML (BIOS) coder actually intended, i.e., there are multiple
solutions to the problem.

What is really being proposed here is for Linux ACPI to be bug-for-bug
compatible with Microsoft.  This is impossible to do deterministically
because the MS interpreter is closed source.  The only standard that we have
that we can code to is the ACPI specification, and this has to be the last
word on the matter.

We have a good opportunity here to help drive the industry to proper BIOS
and ACPI implementations by following the specification and developing tools
(such as the iASL compiler) that help enforce conformance to the ACPI
specification -- and also giving feedback to the BIOS vendors about their
broken ASL code.

Bob Moore


-----Original Message-----
From: Herbert Nachtnebel [mailto:Herbert.Nachtnebel-8zxNtbQCHXIjuwv8T7myQQ@public.gmane.org] 
Sent: Friday, December 13, 2002 1:30 AM
To: NoZizzing OrDripping; acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: AW: [ACPI] [PATCH] Add CONFIG_ACPI_RELAXED_AML option

That's a really bad idea! This size checks are identented to assure, that
important data which accidently follows the buffer can't be overridden by
brain dead bios coders. Now you allow buffer overflow injection into linux
from the bios!
These are serious bios faults, in my DSDT I had to extend a buffer by 128
bytes to avoid a buffer overflow! 
The situation doesn't get better if we ignore such errors. We have to urge
the manufacturers to correct the DSDT's. And the best way to do this is to
recognise the faults and blame them.

Herbert.


> -----Ursprüngliche Nachricht-----
> Von: NoZizzing OrDripping [mailto:nozizzingordripping-/E1597aS9LQAvxtiuMwx3w@public.gmane.org]
> Gesendet: Freitag, 13. Dezember 2002 05:48
> An: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> Betreff: [ACPI] [PATCH] Add CONFIG_ACPI_RELAXED_AML option
> 
> 
> The patch adds a new configuration option,
> CONFIG_ACPI_RELAXED_AML.  When turned on,
> the ACPI code will become forgiving of minor
> errors in the AML code.
> 
> For this first cut, the patch and option will ignore
> region size errors.  An off-by-one error is often
> found in the AML shipped with Toshiba laptops,
> even new models. This minor error prevents the
> AC module from operating without this patch.
> 
> I urge the adoption of this patch (or something
> similar) into the ACPI code.  This will make it
> much easier to install and proliferate Linux on
> a large category of laptops.
> 
> Rick Richardson
> rickr-EySxSuIQeMUAvxtiuMwx3w@public.gmane.org
> [Sorry, have to use my Yahoo account to post to this list)
> 
> __________________________________________________
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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Carlos Morgado]

On 2002.12.13 16:22:43 +0000 "Moore, Robert" wrote:

> 
> What is really being proposed here is for Linux ACPI to be bug-for-bug
> compatible with Microsoft.  This is impossible to do deterministically
> because the MS interpreter is closed source.  The only standard that we have
> that we can code to is the ACPI specification, and this has to be the last
> word on the matter.
> 

not to mention windows tends to ignore builtin dsdts afaik and use the ones
distributed in windows drivers. 
-- 
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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Matthew Tippett]

Carlos Morgado wrote:
> 
> On 2002.12.13 16:22:43 +0000 "Moore, Robert" wrote:
> 
>>
>> What is really being proposed here is for Linux ACPI to be
bug-for-bug
>> compatible with Microsoft.  This is impossible to do
deterministically
>> because the MS interpreter is closed source.  The only standard that 
>> we have
>> that we can code to is the ACPI specification, and this has to be the
>> last
>> word on the matter.
>>
> 
> not to mention windows tends to ignore builtin dsdts afaik and use the
ones
> distributed in windows drivers.

Continuing with this thread, would it make sense to be ACPI compliant 
but allow 'custom' dsdts to be passed to the acpi subsystem to allow 
users to work around less than perfect implementations from
manufacturers.

Although I am not as clued into the inner workings of ACPI, it may be 
extensible to allow developers to highlight to manufacturers where there
dstd is broken and how to have it fixed.

Regards,

Matthew


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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Craig Whitmore]

> > distributed in windows drivers.
>
> Continuing with this thread, would it make sense to be ACPI compliant
> but allow 'custom' dsdts to be passed to the acpi subsystem to allow
> users to work around less than perfect implementations from
> manufacturers.
>

Just 1 question. What do the manufacturer's say when you tell them they have
a "broken" dsdt? Do they normally fix it? or give some excuse in a reason
why they won't fix it?

Thanks
Craig



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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Derek Broughton]

From: "Craig Whitmore" <lennon-q3Ck4f9/EBK9koe0gwxAeg@public.gmane.org>
> > >
> > > Just 1 question. What do the manufacturer's say when you tell them they
> have
> > > a "broken" dsdt? Do they normally fix it? or give some excuse in a
> reason
> > > why they won't fix it?
> >
> > "No we don't.  It works with Windows".
> >
> 
> Even if its breaks the "specs"?

Hey, I didn't make it up.  That's Dell's response to broken DSDTs.



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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Ducrot Bruno]

On Fri, Dec 13, 2002 at 05:18:15PM +0000, Carlos Morgado wrote:
> 
> On 2002.12.13 16:22:43 +0000 "Moore, Robert" wrote:
> 
> >
> >What is really being proposed here is for Linux ACPI to be bug-for-bug
> >compatible with Microsoft.  This is impossible to do deterministically
> >because the MS interpreter is closed source.  The only standard that we 
> >have
> >that we can code to is the ACPI specification, and this has to be the last
> >word on the matter.
> >
> 
> not to mention windows tends to ignore builtin dsdts afaik and use the ones
> distributed in windows drivers. 

I suppose you think perticuliary to their ACPI EC smbus driver?
Well, I don't think that they use a perticular custom dsdt for that.

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Pavel Machek]

Hi!

> I must agree that this is a really bad idea.  Once we start allowing these
> kinds of errors to slip by, there is potentially no end to it.  It's a very
> slippery slope that will potentially plunge everyone into the same kind of
> BIOS abyss that ACPI was intended to solve in the first place.
> 
> Worse, there are situations where the AML interpreter cannot "guess" what
> the ASL/AML (BIOS) coder actually intended, i.e., there are multiple
> solutions to the problem.
> 
> What is really being proposed here is for Linux ACPI to be bug-for-bug
> compatible with Microsoft.  This is impossible to do deterministically
> because the MS interpreter is closed source.  The only standard that we have
> that we can code to is the ACPI specification, and this has to be the last
> word on the matter.

Okay, but we can try. We can for example ignore '*PNP101' and
understand it as 'PNP101', with printk("Star is not valid character in
device name"), which is way more helpufull than /proc/battery does not
exist.

I believe CONFIG_ACPI_RELAXED_AML is good idea.
								Pavel
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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[NoZizzing OrDripping]

--- Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org> wrote:
> Hi!
> > What is really being proposed here is for Linux
> ACPI to be bug-for-bug
> > compatible with Microsoft.  This is impossible to
> do deterministically
> > because the MS interpreter is closed source.  The
> only standard that we have
> > that we can code to is the ACPI specification, and
> this has to be the last
> > word on the matter.
> 
> Okay, but we can try. We can for example ignore
> '*PNP101' and
> understand it as 'PNP101', with printk("Star is not
> valid character in
> device name"), which is way more helpufull than
> /proc/battery does not
> exist.
> 
> I believe CONFIG_ACPI_RELAXED_AML is good idea.
> 								Pavel

The opinions on this are going to break down along the
lines of who has working AML, and who doesn't, with
the tie-breaker going to the distro that wants to
have as many satisfied "customers" as possible.  Right
now, that distro is XP :-(

Anyway, I did a tightened up CONFIG_RELAXED_AML_PATCH
that restricts the slopiness along the lines that Alan
suggested, and also outputs a one-time warning for
any region access violation.

However, a more general implementation would provide
either a global nagged_already bit, or better yet
a per-object nagged_already bit. Or for the most
pedantic, per-object and per-violation-type
nagged_already bits.

Its nasty ugliness, no doubt, but I think that while
strict conformance to standards is a lofty goal, a
loftier goal is for mere mortals to be able to
install Linux on the most popular laptops.

BTW, Best Buy had the Toshiba Satellite 1115-S103 on
sale for only $500 USD yesterday (after $600 in
rebates and markdowns!).  The new bar has been set,
and these
sub-$1000 laptops with buggy AML are going to continue
to profilerate.

If we could agree to add the mechanism, then people
could contribute additional workarounds. It would
still be a controllable feature, turned on only if
desired.

-Rick
rickr-EySxSuIQeMUAvxtiuMwx3w@public.gmane.org


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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Alan Cox]

On Mon, 2002-12-16 at 14:34, NoZizzing OrDripping wrote:
> The opinions on this are going to break down along the
> lines of who has working AML, and who doesn't, with
> the tie-breaker going to the distro that wants to
> have as many satisfied "customers" as possible.  Right
> now, that distro is XP :-(

Intel want people to write valid AML. I don't think they'll ever succeed
but trying doesn't hurt.

Vendors want working laptops

I think the loud complaint approach is the right one. Vendors will get
to look inferior with buggy AML, users get working laptops too.
Certainly its difficult to see a vendor not applying that change.


Alan



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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Andrew Kohlsmith]

> Intel want people to write valid AML. I don't think they'll ever succeed
> but trying doesn't hurt.
>
> Vendors want working laptops

I fail to see why writing valid AML is any more difficult than writing shitty 
AML.  Especially in cases like *PNP0101 vs PNP0101.

But I digress; I know I'm preaching to the converted.  :-)

Regards,
Andrew


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Re: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Carlos Morgado]

On 2002.12.16 14:34:10 +0000 NoZizzing OrDripping wrote:
> 

> BTW, Best Buy had the Toshiba Satellite 1115-S103 on
> sale for only $500 USD yesterday (after $600 in
> rebates and markdowns!).  The new bar has been set,
> and these
> sub-$1000 laptops with buggy AML are going to continue
> to profilerate.
> 

if people pay $500 for a laptop and then complain it doesn't
work you can always tell them they got what they paid for,
a quirky toy.

"quality" AMLs is not a question of price, it's a question
of vendor atitude

-- 
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RE: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Grover, Andrew]

> From: Craig Whitmore [mailto:lennon-q3Ck4f9/EBK9koe0gwxAeg@public.gmane.org] 
> > > distributed in windows drivers.
> >
> > Continuing with this thread, would it make sense to be ACPI 
> compliant
> > but allow 'custom' dsdts to be passed to the acpi subsystem to allow
> > users to work around less than perfect implementations from
> > manufacturers.
> >
> 
> Just 1 question. What do the manufacturer's say when you tell 
> them they have
> a "broken" dsdt? Do they normally fix it? or give some excuse 
> in a reason
> why they won't fix it?

It varies. BIOS bugs exposed by Linux may be prioritized lower due to
Linux's market position in laptops. They also may not get attention if they
are on end-of-lifed machines, or rolled into a BIOS update only when enough
other bugs are fixed to justify a new BIOS's validation and release. (We may
*say* to them it is a trivial fix, but the only way to know if it breaks
Windows is for them to test it!)

There also isn't always a clear way to report BIOS bugs from end users.

On the upside, the things we're seeing are almost always obviously wrong and
easy to fix - it's just getting them to make the trivial change.

Regards -- Andy


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RE: [PATCH] Add CONFIG_ACPI_RELAXED_AML option

[Herbert Nachtnebel]

> 
> Allocating 1 byte of slack, giving a loud warning about the 
> problem and
> erroring if we exceed the 1 byte of slack doesn't sound so bad though?
> 

Sure, that's an option. But look at the presented "fix". 
Just ignoring the error is plain wrong.

Herbert.


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[PATCH] Add CONFIG_ACPI_RELAXED_AML option

[NoZizzing OrDripping]

[-- Attachment #1: Type: text/plain, Size: 839 bytes --]

The patch adds a new configuration option,
CONFIG_ACPI_RELAXED_AML.  When turned on,
the ACPI code will become forgiving of minor
errors in the AML code.

For this first cut, the patch and option will ignore
region size errors.  An off-by-one error is often
found in the AML shipped with Toshiba laptops,
even new models. This minor error prevents the
AC module from operating without this patch.

I urge the adoption of this patch (or something
similar) into the ACPI code.  This will make it
much easier to install and proliferate Linux on
a large category of laptops.

Rick Richardson
rickr-EySxSuIQeMUAvxtiuMwx3w@public.gmane.org
[Sorry, have to use my Yahoo account to post to this list)

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[-- Attachment #2: relaxed-aml.diff --]
[-- Type: application/octet-stream, Size: 2169 bytes --]

diff -u -r linux-2.4.20+acpi-20021205/Documentation/Configure.help linux-2.4.20+acpi-20021205+rick/Documentation/Configure.help
--- linux-2.4.20+acpi-20021205/Documentation/Configure.help	2002-12-12 14:25:15.000000000 -0600
+++ linux-2.4.20+acpi-20021205+rick/Documentation/Configure.help	2002-12-12 13:42:40.000000000 -0600
@@ -18406,6 +18406,14 @@
   of verbosity. Saying Y enables these statements. This will increase
   your kernel size by around 50K.
 
+ACPI Relaxed AML Checking
+CONFIG_ACPI_RELAXED_AML
+  If you say `Y' here, the ACPI interpreter will relax its checking
+  for valid AML and will ignore some AML mistakes, such as off-by-one
+  errors in region sizes.  Some laptps may require this option.  In
+  particular, many Toshiba laptops require this for correct operation
+  of the AC module.
+
 ACPI Bus Manager
 CONFIG_ACPI_BUSMGR
   The ACPI Bus Manager enumerates devices in the ACPI namespace, and
diff -u -r linux-2.4.20+acpi-20021205/drivers/acpi/Config.in linux-2.4.20+acpi-20021205+rick/drivers/acpi/Config.in
--- linux-2.4.20+acpi-20021205/drivers/acpi/Config.in	2002-12-07 08:11:29.000000000 -0600
+++ linux-2.4.20+acpi-20021205+rick/drivers/acpi/Config.in	2002-12-12 13:31:23.000000000 -0600
@@ -36,6 +36,7 @@
       fi
       tristate     '  Toshiba Laptop Extras'	CONFIG_ACPI_TOSHIBA
       bool         '  Debug Statements'	CONFIG_ACPI_DEBUG
+      bool         '  Relaxed AML Checking'	CONFIG_ACPI_RELAXED_AML
     fi
   fi
 
diff -u -r linux-2.4.20+acpi-20021205/drivers/acpi/executer/exfldio.c linux-2.4.20+acpi-20021205+rick/drivers/acpi/executer/exfldio.c
--- linux-2.4.20+acpi-20021205/drivers/acpi/executer/exfldio.c	2002-12-07 08:11:30.000000000 -0600
+++ linux-2.4.20+acpi-20021205+rick/drivers/acpi/executer/exfldio.c	2002-12-12 14:04:49.000000000 -0600
@@ -121,7 +121,11 @@
 			field_datum_byte_offset, obj_desc->common_field.access_byte_width,
 			rgn_desc->region.node->name.ascii, rgn_desc->region.length));
 
-		return_ACPI_STATUS (AE_AML_REGION_LIMIT);
+		#ifdef CONFIG_ACPI_RELAXED_AML
+			return_ACPI_STATUS (AE_OK);
+		#else
+			return_ACPI_STATUS (AE_AML_REGION_LIMIT);
+		#endif
 	}
 
 	return_ACPI_STATUS (AE_OK);