linux-kernel - Re: [PATCH v2 4/7] platform/x86/intel/ifs: Implement Array BIST test

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Date:   Wed, 15 Feb 2023 13:13:40 -0800
From:   "Joseph, Jithu" <jithu.joseph@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>, <hdegoede@...hat.com>,
        <markgross@...nel.org>
CC:     <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
        <gregkh@...uxfoundation.org>, <rostedt@...dmis.org>,
        <ashok.raj@...el.com>, <tony.luck@...el.com>,
        <linux-kernel@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <patches@...ts.linux.dev>,
        <ravi.v.shankar@...el.com>, <thiago.macieira@...el.com>,
        <athenas.jimenez.gonzalez@...el.com>, <sohil.mehta@...el.com>
Subject: Re: [PATCH v2 4/7] platform/x86/intel/ifs: Implement Array BIST test



On 2/15/2023 12:26 PM, Dave Hansen wrote:
> On 2/15/23 12:22, Joseph, Jithu wrote:
>> 		trace_ifs_array(cpu, *((u64 *)&before), *((u64 *)&command));
> 
> Uhh, you control the types in the tracepoint.  Just make them compatible
> so you don't need casts.

will change it to:
trace_ifs_array(cpu, before.array_bitmask, before.array_bank,  *((u64 *)&command));

i.e will pass compatible types for array_list and array_bank. And for the last argument, we need to dump the whole 64 bits within "command"
into trace output . Since the suggested change replaced the union with a struct, it is simplest to cast it to u64 needed by traceoutput.
So I would prefer to keep the cast for the last argument alone.

sample trace output ... 

<snip>
  bash-4562    [001] .....   761.563749: ifs_array: cpu: 10, array_list: 00007fe0, array_bank: 0101, status: 0000000200007fe0
  bash-4562    [001] .....   761.563772: ifs_array: cpu: 10, array_list: 00007fe0, array_bank: 0002, status: 0000010200007fe0
</snip>