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Subject: Re: New warning: PRMT not present
To:     Aubrey Li <aubrey.li@linux.intel.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Len Brown <lenb@kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <64150c95-3f7d-d21f-d6fb-b9d478ed6798@molgen.mpg.de>
 <766862fc-80fa-775b-6e63-6d9422d1d258@molgen.mpg.de>
 <CAJZ5v0i91+kPe4C-wy+oCDvYbR_Vp=MzwEyL+8T3xJU5O4XjRA@mail.gmail.com>
 <c6aaf684-2cd1-f615-34e1-7ef2020ae2d2@molgen.mpg.de>
 <54b6f8cb-4714-587c-b2d0-98134473293d@linux.intel.com>
 <a55ebebc-c8f8-5654-adff-3569d1de2e27@molgen.mpg.de>
 <727d85ff-9efc-42a5-70f1-fcd9fd9e4494@linux.intel.com>
From:   Paul Menzel <pmenzel@molgen.mpg.de>
Message-ID: <e7cbf294-1b0f-cd63-e6cf-3d743e1fe036@molgen.mpg.de>
Date:   Tue, 7 Sep 2021 15:23:15 +0200
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Dear Aubrey,


Am 07.09.21 um 15:02 schrieb Aubrey Li:
> On 9/7/21 3:22 PM, Paul Menzel wrote:

>> Am 07.09.21 um 05:26 schrieb Aubrey Li:
>>
>>> On 9/6/21 10:15 PM, Paul Menzel wrote:
>>
>>>> Am 06.09.21 um 14:02 schrieb Rafael J. Wysocki:
>>>>>
>>>>> This should be addressed by commit 2bbfa0addd63 "ACPI: PRM: Deal with
>>>>> table not present or no module found", or yet another fix is needed.
>>>>
>>>> Linux still warns on my systems with Linux 5.14 and Linus’ master in QEMU i440fx and an Asus F2A85-M PRO.
>>>
>>> Does the following patch address your problem?
>>
>> Yes, it does. With this patch cherry-picked to my Linux tree, the warning is gone in QEMU.
>>
>>      qemu-system-x86_64 -kernel /dev/shm/bzImage -append "earlyprintk=serial,ttyS0,keep console=ttyS0,115200 console=tty0" -display none -serial stdio
>>
>> (I have to check my configuration, why normal serial console does not work in QEMU.)
>>
>>> ----------------------------------------------------------------------
>>>   From 52fda76410fcb7a3661687e960634d34fa44fb5f Mon Sep 17 00:00:00 2001
>>> From: Aubrey Li <aubrey.li@intel.com>
>>> Date: Tue, 7 Sep 2021 11:06:59 +0800
>>> Subject: [PATCH] ACPI/RPM: Find PRMT table before parse it
>>
>> What does RPM mean?
> 
> PRM, Platform Runtime Mechanism:
> https://uefi.org/sites/default/files/resources/Platform%20Runtime%20Mechanism%20-%20with%20legal%20notice.pdf

Ah, so just a typo in the prefix: RPM → PRM.

>>> Find and verify PRMT table before parse it, this eliminates a
>>> warning on machines without PRMT table.
>>
>> Please paste the warning for people grepping the commit messages.
>>
>>      ACPI: PRMT not present
> 
> Nice suggestion.
> 
>>
>>> Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
>>> ---
>>>    drivers/acpi/prmt.c | 10 +++++++++-
>>>    1 file changed, 9 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
>>> index 1f6007a..89c22bc 100644
>>> --- a/drivers/acpi/prmt.c
>>> +++ b/drivers/acpi/prmt.c
>>> @@ -288,10 +288,18 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
>>>      void __init init_prmt(void)
>>>    {
>>> +    struct acpi_table_header *tbl;
>>>        acpi_status status;
>>> -    int mc = acpi_table_parse_entries(ACPI_SIG_PRMT, sizeof(struct acpi_table_prmt) +
>>> +    int mc;
>>> +
>>> +    status = acpi_get_table(ACPI_SIG_PRMT, 0, &tbl);
>>> +    if (ACPI_FAILURE(status))
>>> +        return;
>>> +
>>> +    mc = acpi_table_parse_entries(ACPI_SIG_PRMT, sizeof(struct acpi_table_prmt) +
>>>                          sizeof (struct acpi_table_prmt_header),
>>>                          0, acpi_parse_prmt, 0);
>>> +    acpi_put_table(tbl);
>>>        /*
>>>         * Return immediately if PRMT table is not present or no PRM module found.
>>>         */
>>>
>>
>> Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
> 
> Thanks for testing, I'll send a formal patch to Rafael.

Thank you.


Kind regards,

Paul