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Message-ID: <d0a6ca2d-250a-47e2-8dda-b4e7d74a7ffb@intel.com>
Date:   Fri, 3 Nov 2023 13:23:57 -0700
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Subject: Re: [PATCH v2] x86/resctrl: Fix unused variable warning in
 cache_alloc_hsw_probe()
Content-Language: en-US
To:     "Luck, Tony" <tony.luck@intel.com>,
        "Moger, Babu" <babu.moger@amd.com>
CC:     "Yu, Fenghua" <fenghua.yu@intel.com>,
        Peter Newman <peternewman@google.com>,
        "x86@kernel.org" <x86@kernel.org>,
        Shaopeng Tan <tan.shaopeng@fujitsu.com>,
        James Morse <james.morse@arm.com>,
        Jamie Iles <quic_jiles@quicinc.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "patches@lists.linux.dev" <patches@lists.linux.dev>
References: <20231031220534.37730-1-tony.luck@intel.com>
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From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <SJ1PR11MB6083E6ABE4D467D5D275A309FCA6A@SJ1PR11MB6083.namprd11.prod.outlook.com>
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On 11/2/2023 3:50 PM, Luck, Tony wrote:
>> This does seem a valid issue and my Ack remains. I'm just puzzled why I do not
>> encounter the same warning.
> 
> Reinette,
> 
> Some other CONFIG option changing CFLAGS?
> 
> Here's what I have for a "make V=1 W=1" for core.o
> 

Tony and I went a bit more back-and-forth on this one and it appears that the
relevant code is optimized out in my build while the same did not happen
for him. 

I can now trigger the warning by enabling Xen support, with CONFIG_PARAVIRT_XXL
causing rdmsr() to be replaced by paravirt_read_msr(). With the relevant code
no longer optimized out, the warning is triggered.

Thanks Tony!

Reinette