Date:	Mon, 05 Mar 2012 11:58:55 -0300
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Borislav Petkov <bp@...64.org>
CC:	Tony Luck <tony.luck@...el.com>, Ingo Molnar <mingo@...e.hu>,
	EDAC devel <linux-edac@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] EDAC: Convert AMD EDAC pieces to use RAS printk buffer

Em 05-03-2012 11:13, Borislav Petkov escreveu:
> On Mon, Mar 05, 2012 at 10:35:47AM -0300, Mauro Carvalho Chehab wrote:
>> No. This is an example that you're not reading my emails:
> 
> Unfortunately, I read your emails.
> 
>> no other driver needs that. So, it is something that it is specific to
>> the MCA amd64 drivers.
> 
> Let me spell it for ya: no, it's specific to x86, and not to amd64_edac.

As I'll NACK adding this solution on my drivers, as it makes no sense there,
it is specific to amd64_edac/amd64 mce.

>> The other two MCA drivers are sb_edac and i7core_edac. I wrote both drivers, and they
>> don't need any helper function to store strings on a temporary buffer.
>>
>> Also, the edac core is not x86-specific. So, referencing to a var there (ras_agent) 
>> that it is defined inside arch/x86 would break Kernel compilation on all other 
>> architectures.
> 
> That's more like it.
> 
> It can be moved to an arch-agnostic place or be defined
> __attribute__((weak)) in edac_core.c. Unless someone has a better idea,
> of course.

Well, just fill the string on the way it makes sense for amd64, and then call the
EDAC report function, letting it to call the trace function.

> 
> [..]
> 
>> As already pointed out, you're not reading my emails. The above were at the version 1 of
>> my patches, with I sent at least a month ago. Since version 2, what is proposed is to use:
>>
>> TRACE_EVENT(mc_error_mce,
>>
>> for MCA-based memory error events. There's also a variant for non-MCA drivers (mc_error). 
>>
>> [1] http://git.kernel.org/?p=linux/kernel/git/mchehab/linux-edac.git;a=commitdiff;h=4eb2a29419c1fefd76c8dbcd308b84a4b52faf4d
> 
> I see at least 4 misdesigned tracepoints there:
> 
> trace_mc_out_of_range_mce
> trace_mc_out_of_range
> trace_mc_error_mce
> trace_mc_error
> ...

There's no "..." there. There are just 4 traces defined.
The out of range is an special case to report parse errors.

As I said before, I'm OK to remove the *out_of_range* traces. 

So, there'are just two traces:

	trace_mc_error_mce
	trace_mc_error

E. g. one for the MCA errors, and another one for the non-architecture supported
error handling.

> so NACK to those.
> 
>> I also wrote on my emails that, instead of having a tracepoint
>> specific for memory errors, it is possible to re-define the fields
>> I've proposed to cover CPU location/socket label, and that this is
>> better than folding everything into a hard-to-parse single string
>> message.
> 
> No, this is repurposing the fields of memory errors, which is ugly. So, no.

Then, I it should have 2 MCA error traces:

	- One when the error is inside the CPU socket;
	- Another one when the error is outside the CPU.

Tony,

Please correct me if I'm wrong, but Intel MCA can only point to an error inside
the CPU or a memory error, right? At least, I didn't find there at the x86 arch 
specs anything at the MCA registers that would allow an error to point to the 
PCI bus address for a PCI error, for example.

Regards,
Mauro


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