RE: [PATCH RFC v3 1/6] cxl/trace: Remove uuid from event trace known events

[Shiju Jose]

Hi Ira,

>-----Original Message-----
>From: Ira Weiny <ira.weiny@xxxxxxxxx>
>Sent: 06 November 2023 22:06
>To: Shiju Jose <shiju.jose@xxxxxxxxxx>; Jonathan Cameron
><jonathan.cameron@xxxxxxxxxx>; Ira Weiny <ira.weiny@xxxxxxxxx>
>Cc: Dan Williams <dan.j.williams@xxxxxxxxx>; Smita Koralahalli
><Smita.KoralahalliChannabasappa@xxxxxxx>; Yazen Ghannam
><yazen.ghannam@xxxxxxx>; Davidlohr Bueso <dave@xxxxxxxxxxxx>; Dave
>Jiang <dave.jiang@xxxxxxxxx>; Alison Schofield <alison.schofield@xxxxxxxxx>;
>Vishal Verma <vishal.l.verma@xxxxxxxxx>; Ard Biesheuvel <ardb@xxxxxxxxxx>;
>linux-efi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
>cxl@xxxxxxxxxxxxxxx
>Subject: RE: [PATCH RFC v3 1/6] cxl/trace: Remove uuid from event trace known
>events
>
>Shiju Jose wrote:
>>
>>
>> >-----Original Message-----
>> >From: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
>> >Sent: 03 November 2023 14:28
>> >To: Ira Weiny <ira.weiny@xxxxxxxxx>
>> >Cc: Dan Williams <dan.j.williams@xxxxxxxxx>; Smita Koralahalli
>> ><Smita.KoralahalliChannabasappa@xxxxxxx>; Yazen Ghannam
>> ><yazen.ghannam@xxxxxxx>; Davidlohr Bueso <dave@xxxxxxxxxxxx>; Dave
>> >Jiang <dave.jiang@xxxxxxxxx>; Alison Schofield
>> ><alison.schofield@xxxxxxxxx>; Vishal Verma
>> ><vishal.l.verma@xxxxxxxxx>; Ard Biesheuvel <ardb@xxxxxxxxxx>;
>> >linux-efi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
>> >cxl@xxxxxxxxxxxxxxx; Shiju Jose <shiju.jose@xxxxxxxxxx>
>> >Subject: Re: [PATCH RFC v3 1/6] cxl/trace: Remove uuid from event
>> >trace known events
>> >
>> >On Wed, 01 Nov 2023 14:11:18 -0700
>> >Ira Weiny <ira.weiny@xxxxxxxxx> wrote:
>> >
>> >> The uuid printed in the well known events is redundant.  The uuid
>> >> defines what the event was.
>> >>
>> >> Remove the uuid from the known events and only report it in the
>> >> generic event as it remains informative there.
>> >>
>> >> Reviewed-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
>> >> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>> >> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>> >
>> >Removing the print is fine, but look like this also removes the
>> >actual trace point field.  That's userspace ABI.  Expanding it is
>> >fine, but taking fields away is more problematic.
>> >
>> >Are we sure we don't break anyone?  Shiju, will rasdaemon be fine
>> >with this change?
>>
>> The field hdr_uuid is removed from the common CXL_EVT_TP_entry shared
>> by the trace events cxl_generic_event, cxl_general_media, cxl_dram and
>cxl_memory_module .
>> rasdaemon will break because of this while processing these trace
>> events and also affects the corresponding error records in the SQLite data
>base.
>> Rasdaemon needs update to avoid this.
>>
>
>Ok we can leave the uuid field in easy enough.
>
>But does rasdaemon use the value of the field for anything?  In other words does
>CPER record processing need to generate a proper UUID value?
No. Presently used for logging purpose only in the rasdaemon.

>
>Ira

Thanks,
Shiju