linux-kernel - Re: [ 11.333737] is this a ghost?

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Message-ID: <49230E2C.60101@tuffmail.co.uk>
Date:	Tue, 18 Nov 2008 18:49:16 +0000
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	Len Brown <lenb@...nel.org>
CC:	"Justin P. Mattock" <justinmattock@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux acpi <linux-acpi@...r.kernel.org>
Subject: Re: [ 11.333737] is this a ghost?

Justin P. Mattock wrote:
> On Tue, 2008-11-18 at 16:58 +0000, Alan Jenkins wrote:
>   
>> Justin P. Mattock wrote:
>>     
>>> On Tue, 2008-11-18 at 11:15 +0000, Alan Jenkins wrote:
>>>   
>>>       
>>>> On 11/18/08, Justin P. Mattock <justinmattock@...il.com> wrote:
>>>>     
>>>>         
>>>>> in dmesg I see:
>>>>> [   11.333737]
>>>>> but nothing else.
>>>>>           ---------------(cut)-----------------
>>>>> [   11.247147] Monitor-Mwait will be used to enter C-1 state
>>>>> [   11.247151] Monitor-Mwait will be used to enter C-2 state
>>>>> [   11.247154] Monitor-Mwait will be used to enter C-3 state
>>>>> [   11.247671] ACPI: CPU0 (power states: C1[C1] C2[C2] C3[C3])
>>>>> [   11.247996] processor ACPI_CPU:00: registered as cooling_device0
>>>>> [   11.248008] ACPI: Processor [CPU0] (supports 8 throttling states)
>>>>> [   11.306465] ACPI: SSDT 3FEB8F10, 0087 (r1 APPLE   Cpu1Ist     3000
>>>>> INTL 20050309)<7>power_supply ADP1: No power supply yet
>>>>>       
>>>>>           
>>>> Look at this last line.  The "<7>" is a priority marker.  Normally it
>>>> marks the start of a line, and should be hidden.  So you seem to be
>>>> missing a line break just after "20050309)"...
>>>>
>>>>     
>>>>         
>>>>> [   11.306831] power_supply ADP1: power_supply_changed
>>>>> [   11.306839] ACPI: AC Adapter [ADP1] (on-line)
>>>>> [   11.333737]                         <------------what's with this!!!
>>>>>       
>>>>>           
>>>> ...which seems to be delayed and reappears here?
>>>>
>>>>     
>>>>         
>>>>> [   11.342937] power_supply ADP1: power_supply_changed_work
>>>>> [   11.351901] power_supply ADP1: power_supply_update_gen_leds 1
>>>>> [   11.351916] ACPI: SSDT 3FEB7F10, 0085 (r1 APPLE   Cpu1Cst     3000
>>>>> INTL 20050309)
>>>>>       
>>>>> if you need to see the full dmesg I can attach..
>>>>> I've seen this happen on a random.
>>>>>       
>>>>>           
>>>> I guess you have a multicore processor (or some other sort of SMP), right?
>>>>
>>>> I think kernel messages are not completely synchronized by design, for
>>>> reliability reasons.  (e.g. to make sure critical error messages /
>>>> backtraces can get through on a dying system).
>>>>     
>>>>         
>>> Cool.
>>> makes good sense to me, 
>>> As long as it's not something that shouldn't be there,
>>> or something that's broken. As for this happening again
>>> looking at dmesg nothing, all synchronized.
>>> Seems to randomly show itself.
>>>   
>>>       
>> It's the ACPICA OS abstraction layer - it splits every message into
>> multiple printk() calls.  Other subsystems don't do this... it probably
>> could and should be fixed.
>>
>> drivers/acpi/utmisc.c:
>>
>>     void ACPI_INTERNAL_VAR_XFACE
>>     acpi_ut_info(const char *module_name, u32 line_number, const char
>>     *format, ...)
>>     {
>>         va_list args;
>>
>>         /*
>>          * Removed module_name, line_number, and acpica version, not needed
>>          * for info output
>>          */
>>         acpi_os_printf("ACPI: ");
>>
>>         va_start(args, format);
>>         acpi_os_vprintf(format, args);
>>         acpi_os_printf("\n");
>>         va_end(args);
>>     }
>>
>> The alternative is to use the preprocessor, i.e. macros and string
>> concatenation to generate a single printk().
>>
>> Alan
>>     
>
> Maybe I'm missing a library or something.
> The issue with this is the consistency.
> one reboot I'll see it up higher in dmesg,
> and then on another reboot nothing, then
> maybe a few more reboots I'll see it down lower
> in dmesg(like what I posted). As for fixing this
> I'm not educated enough to go in and exactly know what
> to change(one day hopefully, so I can contribute),
> But I am willing to try a patch out to see if it resolves
> the issue.
>   

Right.  It's simple enough, I can write a patch.  Not sure what would be
most acceptable though.

Len, this sounds like a genuine bug.  Would you accept a patch changing
ACPI_INFO(()) etc. to use GNU-style variadic macros?

Thanks
Alan
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