Re: [PATCH -v4] x86: MCE: Re-implement MCE log ring buffer as per-CPU ring buffer

Hidetoshi Seto
2009-06-05T08:29:06Z

> On Fri, 2009-06-05 at 15:01 +0800, Hidetoshi Seto wrote:
>> Huang Ying wrote:
>>> struct mce_log {
>>> - char signature[12]; /* "MACHINECHECK" */
>>> + char signature[12]; /* "MACHINECHEC2" */
>>> unsigned len; /* = MCE_LOG_LEN */
>>> - unsigned next;
>>> unsigned flags;
>>> unsigned pad0;
>>> - struct mce entry[MCE_LOG_LEN];
>>> + struct mce_log_cpu *mcelog_cpus;
>>> };
>> What is this *mcelog_cpus to be used for?
>> It seems it will point one of per-CPU buffers (maybe cpu#0's buffer)
>> if I have read the following mce_log_init() correctly.
>
> It is mainly used by something like kdump, which can search
> "MACHINECHEC2", and analyze mce_log. mcelog_cpus can help kdump find the
> real mcelog storage.

Hum, but it help tools only to find one of buffers, not to find all.

I think it would be better help for tools if we have another signature
on struct mce_log_cpu, e.g.:

+struct mce_log_cpu {
+ char signature[**]; /* "MCE_LOG_CPU_VER_1" or so */
+ __u32 cpuid; /* cpuid or extcpu, same as struct mce */
+ int head;
+ int tail;
+ unsigned long flags;
+ struct mce entry[MCE_LOG_LEN];
+};

How about this?

Thanks,
H.Seto