[Devel] GPE blocks in reduced hardware mode

[Devel] GPE blocks in reduced hardware mode

[Al Stone]

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Howdy.

I've been trying to do some clean-up on the Linux ACPI driver with
regard to the reduced hardware profile introduced in ACPI 5.0.

In thinking about GPE block devices, I was looking through the
functions in source/components/events/evxfgpe.c and noticed that
they are all #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look
back through the specification, however, I cannot find any place
where they are prohibited.

Clearly, the gpe0/1 blocks in the FADT are not to be used; this
is explicitly stated in section 5.2.9 of the spec.  Could someone
please point me to a similar statement for a GPE block device?  I
just cannot seem to find it.

The closest thing I can find is section 9.10 implying that a GPE
block device is an extension of the gpe0/1 blocks from the FADT,
but there is no explicit statement there so it is ambiguous to me.

Thanks in advance for any pointers; I'm just puzzled at this point
and trying to understand how the conclusion came to be.

-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3(a)redhat.com
-----------------------------------

Re: [Devel] GPE blocks in reduced hardware mode

[Moore, Robert]

[-- Attachment #1: Type: text/plain, Size: 1927 bytes --]

The first thing is that there are no GPE block devices in the field, never have been. I don't think ACPICA actually supports them fully. It is a bit of an "orphan" feature of ACPI.

I'll have to take a look closer at the spec for an exact reference, but basically one of the things that ACPI_REDUCED_HARDWARE means is no GPEs, IIRC.

> -----Original Message-----
> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone
> Sent: Tuesday, December 03, 2013 2:38 PM
> To: devel(a)acpica.org
> Subject: [Devel] GPE blocks in reduced hardware mode
> 
> Howdy.
> 
> I've been trying to do some clean-up on the Linux ACPI driver with regard
> to the reduced hardware profile introduced in ACPI 5.0.
> 
> In thinking about GPE block devices, I was looking through the functions
> in source/components/events/evxfgpe.c and noticed that they are all
> #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look back through the
> specification, however, I cannot find any place where they are prohibited.
> 
> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
> explicitly stated in section 5.2.9 of the spec.  Could someone please
> point me to a similar statement for a GPE block device?  I just cannot
> seem to find it.
> 
> The closest thing I can find is section 9.10 implying that a GPE block
> device is an extension of the gpe0/1 blocks from the FADT, but there is no
> explicit statement there so it is ambiguous to me.
> 
> Thanks in advance for any pointers; I'm just puzzled at this point and
> trying to understand how the conclusion came to be.
> 
> --
> ciao,
> al
> -----------------------------------
> Al Stone
> Software Engineer
> Red Hat, Inc.
> ahs3(a)redhat.com
> -----------------------------------
> _______________________________________________
> Devel mailing list
> Devel(a)acpica.org
> https://lists.acpica.org/mailman/listinfo/devel

Re: [Devel] GPE blocks in reduced hardware mode

[Al Stone]

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On 12/03/2013 05:18 PM, Moore, Robert wrote:
> The first thing is that there are no GPE block devices in the field, never have been. I don't think ACPICA actually supports them fully. It is a bit of an "orphan" feature of ACPI.

I see.  Yeah, I did find GPE block device support confusing in the
code.  It seems like the infrastructure to handle them is present,
but there is no code to handle the "ACPI0006" ID anywhere I can find
(that may be a Linux limitation, though).

> I'll have to take a look closer at the spec for an exact reference, but basically one of the things that ACPI_REDUCED_HARDWARE means is no GPEs, IIRC.

Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code;
that seems pretty clear.  I just can't seem to find anything that clear
in the spec :/...

I'll continue to look in the spec but if you find something before I
do, do let me know.

Thanks!

>> -----Original Message-----
>> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone
>> Sent: Tuesday, December 03, 2013 2:38 PM
>> To: devel(a)acpica.org
>> Subject: [Devel] GPE blocks in reduced hardware mode
>>
>> Howdy.
>>
>> I've been trying to do some clean-up on the Linux ACPI driver with regard
>> to the reduced hardware profile introduced in ACPI 5.0.
>>
>> In thinking about GPE block devices, I was looking through the functions
>> in source/components/events/evxfgpe.c and noticed that they are all
>> #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look back through the
>> specification, however, I cannot find any place where they are prohibited.
>>
>> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
>> explicitly stated in section 5.2.9 of the spec.  Could someone please
>> point me to a similar statement for a GPE block device?  I just cannot
>> seem to find it.
>>
>> The closest thing I can find is section 9.10 implying that a GPE block
>> device is an extension of the gpe0/1 blocks from the FADT, but there is no
>> explicit statement there so it is ambiguous to me.
>>
>> Thanks in advance for any pointers; I'm just puzzled at this point and
>> trying to understand how the conclusion came to be.
>>
>> --
>> ciao,
>> al
>> -----------------------------------
>> Al Stone
>> Software Engineer
>> Red Hat, Inc.
>> ahs3(a)redhat.com
>> -----------------------------------
>> _______________________________________________
>> Devel mailing list
>> Devel(a)acpica.org
>> https://lists.acpica.org/mailman/listinfo/devel


-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3(a)redhat.com
-----------------------------------

Re: [Devel] GPE blocks in reduced hardware mode

[Moore, Robert]

[-- Attachment #1: Type: text/plain, Size: 3554 bytes --]



> -----Original Message-----
> From: Al Stone [mailto:ahs3(a)redhat.com]
> Sent: Tuesday, December 03, 2013 5:39 PM
> To: Moore, Robert; devel(a)acpica.org
> Subject: Re: [Devel] GPE blocks in reduced hardware mode
> 
> On 12/03/2013 05:18 PM, Moore, Robert wrote:
> > The first thing is that there are no GPE block devices in the field,
> never have been. I don't think ACPICA actually supports them fully. It is
> a bit of an "orphan" feature of ACPI.
> 
> I see.  Yeah, I did find GPE block device support confusing in the code.
> It seems like the infrastructure to handle them is present, but there is
> no code to handle the "ACPI0006" ID anywhere I can find (that may be a
> Linux limitation, though).


Correct. There needs to be a linux driver that is loaded upon detection of an _HID of ACPI0006. This does not exist. Thus, there is no support for this feature in Linux.

The GPE block device was a bit of a fantasy that never materialized in any hardware that I know of. And one could certainly conclude with some high degree of probability that nobody is going to implement custom hardware to support a GPE block device on a (ahem) "hardware reduced platform".

Bob




> 
> > I'll have to take a look closer at the spec for an exact reference, but
> basically one of the things that ACPI_REDUCED_HARDWARE means is no GPEs,
> IIRC.
> 
> Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code; that
> seems pretty clear.  I just can't seem to find anything that clear in the
> spec :/...
> 
> I'll continue to look in the spec but if you find something before I do,
> do let me know.
> 
> Thanks!
> 
> >> -----Original Message-----
> >> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone
> >> Sent: Tuesday, December 03, 2013 2:38 PM
> >> To: devel(a)acpica.org
> >> Subject: [Devel] GPE blocks in reduced hardware mode
> >>
> >> Howdy.
> >>
> >> I've been trying to do some clean-up on the Linux ACPI driver with
> >> regard to the reduced hardware profile introduced in ACPI 5.0.
> >>
> >> In thinking about GPE block devices, I was looking through the
> >> functions in source/components/events/evxfgpe.c and noticed that they
> >> are all #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look back
> >> through the specification, however, I cannot find any place where they
> are prohibited.
> >>
> >> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
> >> explicitly stated in section 5.2.9 of the spec.  Could someone please
> >> point me to a similar statement for a GPE block device?  I just
> >> cannot seem to find it.
> >>
> >> The closest thing I can find is section 9.10 implying that a GPE
> >> block device is an extension of the gpe0/1 blocks from the FADT, but
> >> there is no explicit statement there so it is ambiguous to me.
> >>
> >> Thanks in advance for any pointers; I'm just puzzled at this point
> >> and trying to understand how the conclusion came to be.
> >>
> >> --
> >> ciao,
> >> al
> >> -----------------------------------
> >> Al Stone
> >> Software Engineer
> >> Red Hat, Inc.
> >> ahs3(a)redhat.com
> >> -----------------------------------
> >> _______________________________________________
> >> Devel mailing list
> >> Devel(a)acpica.org
> >> https://lists.acpica.org/mailman/listinfo/devel
> 
> 
> --
> ciao,
> al
> -----------------------------------
> Al Stone
> Software Engineer
> Red Hat, Inc.
> ahs3(a)redhat.com
> -----------------------------------

Re: [Devel] GPE blocks in reduced hardware mode

[Moore, Robert]

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Some text pulled from the ACPI 5.0 Spec:


5.6 ACPI Event Programming Model
The ACPI event programming model is based on the SCI interrupt and General-Purpose Event (GPE) register. ACPI provides an extensible method to raise and handle the SCI interrupt, as described in this section.
Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connections to signal ACPI Events, described in Section 5.6.5.


5.6.1 ACPI Event Programming Model Components
The components of the ACPI event programming model are the following:
* OSPM
* FADT
* PM1a_STS, PM1b_STS and PM1a_EN, PM1b_EN fixed register blocks
* GPE0_BLK and GPE1_BLK register blocks
* GPE register blocks defined in GPE block devices


5.6.5 GPIO-signaled ACPI Events
On Hardware-reduced ACPI platforms, ACPI events are signaled when a GPIO Interrupt is received by OSPM,


7.2.13 PRW (Power Resources for Wake)
For HW-Reduced ACPI platforms, the GpeInfo structure is ignored by OSPM.


>> Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connections to signal ACPI Events.

I think this sentence says that on hardware-reduced ACPI platforms, there are no GPEs, period.
Bob


> -----Original Message-----
> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Moore, Robert
> Sent: Tuesday, December 03, 2013 10:28 PM
> To: Al Stone; devel(a)acpica.org
> Subject: Re: [Devel] GPE blocks in reduced hardware mode
> 
> 
> 
> > -----Original Message-----
> > From: Al Stone [mailto:ahs3(a)redhat.com]
> > Sent: Tuesday, December 03, 2013 5:39 PM
> > To: Moore, Robert; devel(a)acpica.org
> > Subject: Re: [Devel] GPE blocks in reduced hardware mode
> >
> > On 12/03/2013 05:18 PM, Moore, Robert wrote:
> > > The first thing is that there are no GPE block devices in the field,
> > never have been. I don't think ACPICA actually supports them fully. It
> > is a bit of an "orphan" feature of ACPI.
> >
> > I see.  Yeah, I did find GPE block device support confusing in the code.
> > It seems like the infrastructure to handle them is present, but there
> > is no code to handle the "ACPI0006" ID anywhere I can find (that may
> > be a Linux limitation, though).
> 
> 
> Correct. There needs to be a linux driver that is loaded upon detection of
> an _HID of ACPI0006. This does not exist. Thus, there is no support for
> this feature in Linux.
> 
> The GPE block device was a bit of a fantasy that never materialized in any
> hardware that I know of. And one could certainly conclude with some high
> degree of probability that nobody is going to implement custom hardware to
> support a GPE block device on a (ahem) "hardware reduced platform".
> 
> Bob
> 
> 
> 
> 
> >
> > > I'll have to take a look closer at the spec for an exact reference,
> > > but
> > basically one of the things that ACPI_REDUCED_HARDWARE means is no
> > GPEs, IIRC.
> >
> > Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code;
> > that seems pretty clear.  I just can't seem to find anything that
> > clear in the spec :/...
> >
> > I'll continue to look in the spec but if you find something before I
> > do, do let me know.
> >
> > Thanks!
> >
> > >> -----Original Message-----
> > >> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone
> > >> Sent: Tuesday, December 03, 2013 2:38 PM
> > >> To: devel(a)acpica.org
> > >> Subject: [Devel] GPE blocks in reduced hardware mode
> > >>
> > >> Howdy.
> > >>
> > >> I've been trying to do some clean-up on the Linux ACPI driver with
> > >> regard to the reduced hardware profile introduced in ACPI 5.0.
> > >>
> > >> In thinking about GPE block devices, I was looking through the
> > >> functions in source/components/events/evxfgpe.c and noticed that
> > >> they are all #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look
> > >> back through the specification, however, I cannot find any place
> > >> where they
> > are prohibited.
> > >>
> > >> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
> > >> explicitly stated in section 5.2.9 of the spec.  Could someone
> > >> please point me to a similar statement for a GPE block device?  I
> > >> just cannot seem to find it.
> > >>
> > >> The closest thing I can find is section 9.10 implying that a GPE
> > >> block device is an extension of the gpe0/1 blocks from the FADT,
> > >> but there is no explicit statement there so it is ambiguous to me.
> > >>
> > >> Thanks in advance for any pointers; I'm just puzzled at this point
> > >> and trying to understand how the conclusion came to be.
> > >>
> > >> --
> > >> ciao,
> > >> al
> > >> -----------------------------------
> > >> Al Stone
> > >> Software Engineer
> > >> Red Hat, Inc.
> > >> ahs3(a)redhat.com
> > >> -----------------------------------
> > >> _______________________________________________
> > >> Devel mailing list
> > >> Devel(a)acpica.org
> > >> https://lists.acpica.org/mailman/listinfo/devel
> >
> >
> > --
> > ciao,
> > al
> > -----------------------------------
> > Al Stone
> > Software Engineer
> > Red Hat, Inc.
> > ahs3(a)redhat.com
> > -----------------------------------
> _______________________________________________
> Devel mailing list
> Devel(a)acpica.org
> https://lists.acpica.org/mailman/listinfo/devel

Re: [Devel] GPE blocks in reduced hardware mode

[Al Stone]

[-- Attachment #1: Type: text/plain, Size: 5993 bytes --]

On 12/04/2013 08:51 AM, Moore, Robert wrote:
> Some text pulled from the ACPI 5.0 Spec:
>
>
> 5.6 ACPI Event Programming Model
> The ACPI event programming model is based on the SCI interrupt and General-Purpose Event (GPE) register. ACPI provides an extensible method to raise and handle the SCI interrupt, as described in this section.
> Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connections to signal ACPI Events, described in Section 5.6.5.
>
>
> 5.6.1 ACPI Event Programming Model Components
> The components of the ACPI event programming model are the following:
> * OSPM
> * FADT
> * PM1a_STS, PM1b_STS and PM1a_EN, PM1b_EN fixed register blocks
> * GPE0_BLK and GPE1_BLK register blocks
> * GPE register blocks defined in GPE block devices
>
>
> 5.6.5 GPIO-signaled ACPI Events
> On Hardware-reduced ACPI platforms, ACPI events are signaled when a GPIO Interrupt is received by OSPM,
>
>
> 7.2.13 PRW (Power Resources for Wake)
> For HW-Reduced ACPI platforms, the GpeInfo structure is ignored by OSPM.
>
>
>>> Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connections to signal ACPI Events.
>
> I think this sentence says that on hardware-reduced ACPI platforms, there are no GPEs, period.
> Bob

Thanks for the pointers; I'm afraid I can't add anything to that
list -- it matches what I came up with when I scanned again last
night.

I agree with you that the spec is saying are no GPEs in hardware
reduced, but I think it is implied, versus it being stated explicitly.
And that's where I get a bit puzzled.

I'll take this up with the ASWG and see if I can get some sort of
unambiguous wording added in.

>> -----Original Message-----
>> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Moore, Robert
>> Sent: Tuesday, December 03, 2013 10:28 PM
>> To: Al Stone; devel(a)acpica.org
>> Subject: Re: [Devel] GPE blocks in reduced hardware mode
>>
>>
>>
>>> -----Original Message-----
>>> From: Al Stone [mailto:ahs3(a)redhat.com]
>>> Sent: Tuesday, December 03, 2013 5:39 PM
>>> To: Moore, Robert; devel(a)acpica.org
>>> Subject: Re: [Devel] GPE blocks in reduced hardware mode
>>>
>>> On 12/03/2013 05:18 PM, Moore, Robert wrote:
>>>> The first thing is that there are no GPE block devices in the field,
>>> never have been. I don't think ACPICA actually supports them fully. It
>>> is a bit of an "orphan" feature of ACPI.
>>>
>>> I see.  Yeah, I did find GPE block device support confusing in the code.
>>> It seems like the infrastructure to handle them is present, but there
>>> is no code to handle the "ACPI0006" ID anywhere I can find (that may
>>> be a Linux limitation, though).
>>
>>
>> Correct. There needs to be a linux driver that is loaded upon detection of
>> an _HID of ACPI0006. This does not exist. Thus, there is no support for
>> this feature in Linux.
>>
>> The GPE block device was a bit of a fantasy that never materialized in any
>> hardware that I know of. And one could certainly conclude with some high
>> degree of probability that nobody is going to implement custom hardware to
>> support a GPE block device on a (ahem) "hardware reduced platform".
>>
>> Bob
>>
>>
>>
>>
>>>
>>>> I'll have to take a look closer at the spec for an exact reference,
>>>> but
>>> basically one of the things that ACPI_REDUCED_HARDWARE means is no
>>> GPEs, IIRC.
>>>
>>> Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code;
>>> that seems pretty clear.  I just can't seem to find anything that
>>> clear in the spec :/...
>>>
>>> I'll continue to look in the spec but if you find something before I
>>> do, do let me know.
>>>
>>> Thanks!
>>>
>>>>> -----Original Message-----
>>>>> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone
>>>>> Sent: Tuesday, December 03, 2013 2:38 PM
>>>>> To: devel(a)acpica.org
>>>>> Subject: [Devel] GPE blocks in reduced hardware mode
>>>>>
>>>>> Howdy.
>>>>>
>>>>> I've been trying to do some clean-up on the Linux ACPI driver with
>>>>> regard to the reduced hardware profile introduced in ACPI 5.0.
>>>>>
>>>>> In thinking about GPE block devices, I was looking through the
>>>>> functions in source/components/events/evxfgpe.c and noticed that
>>>>> they are all #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look
>>>>> back through the specification, however, I cannot find any place
>>>>> where they
>>> are prohibited.
>>>>>
>>>>> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
>>>>> explicitly stated in section 5.2.9 of the spec.  Could someone
>>>>> please point me to a similar statement for a GPE block device?  I
>>>>> just cannot seem to find it.
>>>>>
>>>>> The closest thing I can find is section 9.10 implying that a GPE
>>>>> block device is an extension of the gpe0/1 blocks from the FADT,
>>>>> but there is no explicit statement there so it is ambiguous to me.
>>>>>
>>>>> Thanks in advance for any pointers; I'm just puzzled at this point
>>>>> and trying to understand how the conclusion came to be.
>>>>>
>>>>> --
>>>>> ciao,
>>>>> al
>>>>> -----------------------------------
>>>>> Al Stone
>>>>> Software Engineer
>>>>> Red Hat, Inc.
>>>>> ahs3(a)redhat.com
>>>>> -----------------------------------
>>>>> _______________________________________________
>>>>> Devel mailing list
>>>>> Devel(a)acpica.org
>>>>> https://lists.acpica.org/mailman/listinfo/devel
>>>
>>>
>>> --
>>> ciao,
>>> al
>>> -----------------------------------
>>> Al Stone
>>> Software Engineer
>>> Red Hat, Inc.
>>> ahs3(a)redhat.com
>>> -----------------------------------
>> _______________________________________________
>> Devel mailing list
>> Devel(a)acpica.org
>> https://lists.acpica.org/mailman/listinfo/devel


-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3(a)redhat.com
-----------------------------------

Re: [Devel] GPE blocks in reduced hardware mode

[Moore, Robert]

[-- Attachment #1: Type: text/plain, Size: 6637 bytes --]



> -----Original Message-----
> From: Al Stone [mailto:ahs3(a)redhat.com]
> Sent: Thursday, December 05, 2013 8:24 AM
> To: Moore, Robert; devel(a)acpica.org
> Subject: Re: [Devel] GPE blocks in reduced hardware mode
> 
> On 12/04/2013 08:51 AM, Moore, Robert wrote:
> > Some text pulled from the ACPI 5.0 Spec:
> >
> >
> > 5.6 ACPI Event Programming Model
> > The ACPI event programming model is based on the SCI interrupt and
> General-Purpose Event (GPE) register. ACPI provides an extensible method
> to raise and handle the SCI interrupt, as described in this section.
> > Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt
> Connections to signal ACPI Events, described in Section 5.6.5.
> >
> >
> > 5.6.1 ACPI Event Programming Model Components The components of the
> > ACPI event programming model are the following:
> > * OSPM
> > * FADT
> > * PM1a_STS, PM1b_STS and PM1a_EN, PM1b_EN fixed register blocks
> > * GPE0_BLK and GPE1_BLK register blocks
> > * GPE register blocks defined in GPE block devices
> >
> >
> > 5.6.5 GPIO-signaled ACPI Events
> > On Hardware-reduced ACPI platforms, ACPI events are signaled when a
> > GPIO Interrupt is received by OSPM,
> >
> >
> > 7.2.13 PRW (Power Resources for Wake)
> > For HW-Reduced ACPI platforms, the GpeInfo structure is ignored by OSPM.
> >
> >
> >>> Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt
> Connections to signal ACPI Events.
> >
> > I think this sentence says that on hardware-reduced ACPI platforms,
> there are no GPEs, period.
> > Bob
> 
> Thanks for the pointers; I'm afraid I can't add anything to that list --
> it matches what I came up with when I scanned again last night.
> 
> I agree with you that the spec is saying are no GPEs in hardware reduced,
> but I think it is implied, versus it being stated explicitly.
> And that's where I get a bit puzzled.


Welcome to the ACPI spec :-)



> 
> I'll take this up with the ASWG and see if I can get some sort of
> unambiguous wording added in.
> 
> >> -----Original Message-----
> >> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Moore,
> >> Robert
> >> Sent: Tuesday, December 03, 2013 10:28 PM
> >> To: Al Stone; devel(a)acpica.org
> >> Subject: Re: [Devel] GPE blocks in reduced hardware mode
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: Al Stone [mailto:ahs3(a)redhat.com]
> >>> Sent: Tuesday, December 03, 2013 5:39 PM
> >>> To: Moore, Robert; devel(a)acpica.org
> >>> Subject: Re: [Devel] GPE blocks in reduced hardware mode
> >>>
> >>> On 12/03/2013 05:18 PM, Moore, Robert wrote:
> >>>> The first thing is that there are no GPE block devices in the
> >>>> field,
> >>> never have been. I don't think ACPICA actually supports them fully.
> >>> It is a bit of an "orphan" feature of ACPI.
> >>>
> >>> I see.  Yeah, I did find GPE block device support confusing in the
> code.
> >>> It seems like the infrastructure to handle them is present, but
> >>> there is no code to handle the "ACPI0006" ID anywhere I can find
> >>> (that may be a Linux limitation, though).
> >>
> >>
> >> Correct. There needs to be a linux driver that is loaded upon
> >> detection of an _HID of ACPI0006. This does not exist. Thus, there is
> >> no support for this feature in Linux.
> >>
> >> The GPE block device was a bit of a fantasy that never materialized
> >> in any hardware that I know of. And one could certainly conclude with
> >> some high degree of probability that nobody is going to implement
> >> custom hardware to support a GPE block device on a (ahem) "hardware
> reduced platform".
> >>
> >> Bob
> >>
> >>
> >>
> >>
> >>>
> >>>> I'll have to take a look closer at the spec for an exact reference,
> >>>> but
> >>> basically one of the things that ACPI_REDUCED_HARDWARE means is no
> >>> GPEs, IIRC.
> >>>
> >>> Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code;
> >>> that seems pretty clear.  I just can't seem to find anything that
> >>> clear in the spec :/...
> >>>
> >>> I'll continue to look in the spec but if you find something before I
> >>> do, do let me know.
> >>>
> >>> Thanks!
> >>>
> >>>>> -----Original Message-----
> >>>>> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al
> >>>>> Stone
> >>>>> Sent: Tuesday, December 03, 2013 2:38 PM
> >>>>> To: devel(a)acpica.org
> >>>>> Subject: [Devel] GPE blocks in reduced hardware mode
> >>>>>
> >>>>> Howdy.
> >>>>>
> >>>>> I've been trying to do some clean-up on the Linux ACPI driver with
> >>>>> regard to the reduced hardware profile introduced in ACPI 5.0.
> >>>>>
> >>>>> In thinking about GPE block devices, I was looking through the
> >>>>> functions in source/components/events/evxfgpe.c and noticed that
> >>>>> they are all #ifdef'd out for ACPI_REDUCED_HARDWARE.  When I look
> >>>>> back through the specification, however, I cannot find any place
> >>>>> where they
> >>> are prohibited.
> >>>>>
> >>>>> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is
> >>>>> explicitly stated in section 5.2.9 of the spec.  Could someone
> >>>>> please point me to a similar statement for a GPE block device?  I
> >>>>> just cannot seem to find it.
> >>>>>
> >>>>> The closest thing I can find is section 9.10 implying that a GPE
> >>>>> block device is an extension of the gpe0/1 blocks from the FADT,
> >>>>> but there is no explicit statement there so it is ambiguous to me.
> >>>>>
> >>>>> Thanks in advance for any pointers; I'm just puzzled at this point
> >>>>> and trying to understand how the conclusion came to be.
> >>>>>
> >>>>> --
> >>>>> ciao,
> >>>>> al
> >>>>> -----------------------------------
> >>>>> Al Stone
> >>>>> Software Engineer
> >>>>> Red Hat, Inc.
> >>>>> ahs3(a)redhat.com
> >>>>> -----------------------------------
> >>>>> _______________________________________________
> >>>>> Devel mailing list
> >>>>> Devel(a)acpica.org
> >>>>> https://lists.acpica.org/mailman/listinfo/devel
> >>>
> >>>
> >>> --
> >>> ciao,
> >>> al
> >>> -----------------------------------
> >>> Al Stone
> >>> Software Engineer
> >>> Red Hat, Inc.
> >>> ahs3(a)redhat.com
> >>> -----------------------------------
> >> _______________________________________________
> >> Devel mailing list
> >> Devel(a)acpica.org
> >> https://lists.acpica.org/mailman/listinfo/devel
> 
> 
> --
> ciao,
> al
> -----------------------------------
> Al Stone
> Software Engineer
> Red Hat, Inc.
> ahs3(a)redhat.com
> -----------------------------------