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Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded error

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On Thu, Jul 27, 2017 at 09:10:34AM +0200, Ingo Molnar wrote:
> Looks pretty nice to me conceptually. Do you have a couple of examples of 
> real-life events that get logged? It's hard to decode it from the new tracepoint 
> alone.

Here's what comes out in dmesg:

[  932.370319] mce: [Hardware Error]: Machine check events logged
[  932.374474] [Hardware Error]: Corrected error, no action required.
[  932.381684] [Hardware Error]: CPU:1 (0:0:0) MC5_STATUS[Over|CE|MiscV|-|AddrV|CECC]: 0xdc00410000020f0f
[  932.384256] [Hardware Error]: Error Addr: 0x0000000056071033 [Hardware Error]: TSC: 2703436211649
[  932.386608] [Hardware Error]: MC5 Error: AG payload array parity error.
[  932.388425] [Hardware Error]: cache level: L3/GEN, mem/io: GEN, mem-tx: GEN, part-proc: GEN (timed out)

(whoops, that TSC thing should be on a new line).

and the TP dumps only the last two lines:

[  932.386608] [Hardware Error]: MC5 Error: AG payload array parity error.
[  932.388425] [Hardware Error]: cache level: L3/GEN, mem/io: GEN, mem-tx: GEN, part-proc: GEN (timed out)

but come to think of it, it should dump only the MC? Error line because
the last line can be easily deduced from the error code. I'll change
that.

Btw, the reason why I'm dumping only MC? line is to keep the string
going into the TP relatively small. It is 128 bytes now. I tried dumping
the whole decoded string but that easily overflowed 256 bytes and 256
bytes is already a bit too much to log into the trace buffers.

So I'm concentrating only on the not-very-trivial stuff to decode.

The rest is being deduced directly from the MCi_STATUS value anyway
which we can easily do in userspace and that is straightforward. And
that u64 value we already dump with trace_mce_record().

So the idea is, userspace opens trace_mce_record() to get the raw MCE
data and then this second TP to get the decoded string of what that
error is.

Later, we could extend that same behavior to Intel for the common
errors, at least, so that we can dump at least *some* string explaining
what the error is.

Anyway, something like that is swirling in my head right now...

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--

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[RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded error Borislav Petkov <bp@alien8.de> - 2017-07-25 17:50 +0200
  [RFC PATCH 4/8] seq_buf: Add seq_buf_clear_buf() Borislav Petkov <bp@alien8.de> - 2017-07-25 17:50 +0200
    Re: [RFC PATCH 4/8] seq_buf: Add seq_buf_clear_buf() Steven Rostedt <rostedt@goodmis.org> - 2017-07-28 03:50 +0200
  [RFC PATCH 1/8] EDAC, mce_amd: Rename decode_smca_errors() to decode_smca_error() Borislav Petkov <bp@alien8.de> - 2017-07-25 17:50 +0200
  [RFC PATCH 3/8] EDAC, mce_amd: Get rid of local var in amd_filter_mce() Borislav Petkov <bp@alien8.de> - 2017-07-25 17:50 +0200
  [RFC PATCH 8/8] EDAC, mce_amd: Issue the decoded info through the TP or printk Borislav Petkov <bp@alien8.de> - 2017-07-25 18:00 +0200
  [RFC PATCH 5/8] seq_buf: Export seq_buf_printf() to modules Borislav Petkov <bp@alien8.de> - 2017-07-25 18:00 +0200
    Re: [RFC PATCH 5/8] seq_buf: Export seq_buf_printf() to modules Steven Rostedt <rostedt@goodmis.org> - 2017-07-28 03:50 +0200
  [RFC PATCH 7/8] EDAC, mce_amd: Add a simple tracepoint dumping a decoded string Borislav Petkov <bp@alien8.de> - 2017-07-25 18:00 +0200
    Re: [RFC PATCH 7/8] EDAC, mce_amd: Add a simple tracepoint dumping  a decoded string Steven Rostedt <rostedt@goodmis.org> - 2017-07-28 03:50 +0200
      Re: [RFC PATCH 7/8] EDAC, mce_amd: Add a simple tracepoint dumping a  decoded string Borislav Petkov <bp@alien8.de> - 2017-07-28 09:20 +0200
  [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Borislav Petkov <bp@alien8.de> - 2017-07-25 18:00 +0200
    Re: [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Steven Rostedt <rostedt@goodmis.org> - 2017-07-28 03:50 +0200
      Re: [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Borislav Petkov <bp@alien8.de> - 2017-07-28 09:20 +0200
        Re: [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Borislav Petkov <bp@alien8.de> - 2017-07-28 13:00 +0200
          Re: [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Steven Rostedt <rostedt@goodmis.org> - 2017-07-28 15:10 +0200
            Re: [RFC PATCH 6/8] EDAC, mce_amd: Convert to seq_buf Borislav Petkov <bp@alien8.de> - 2017-07-28 16:20 +0200
  Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Ingo Molnar <mingo@kernel.org> - 2017-07-27 09:20 +0200
    Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-27 10:00 +0200
      Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Ingo Molnar <mingo@kernel.org> - 2017-07-27 10:40 +0200
        Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-27 15:10 +0200
          Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Ingo Molnar <mingo@kernel.org> - 2017-07-28 08:40 +0200
            Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-28 09:20 +0200
              Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-28 17:10 +0200
                Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-28 17:40 +0200
      RE: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error "Luck, Tony" <tony.luck@intel.com> - 2017-07-27 18:50 +0200
        Re: [RFC PATCH 0/8] EDAC, mce_amd: Add a tracepoint for the decoded  error Borislav Petkov <bp@alien8.de> - 2017-07-28 09:30 +0200

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