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From: Dave Hansen <dave.hansen@intel.com>
To: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Tony Luck <tony.luck@intel.com>, Len Brown <len.brown@intel.com>,
	Borislav Petkov <bp@suse.de>,
	x86@kernel.org
Subject: Re: [tip: perf/core] x86/cpu: Add helper function to get the type of the current hybrid CPU
Date: Fri, 5 May 2023 09:42:36 -0700	[thread overview]
Message-ID: <55343361-d991-c157-4a88-843947aa45ff@intel.com> (raw)
In-Reply-To: <161891560955.29796.10811256921836669612.tip-bot2@tip-bot2>

On 4/20/21 03:46, tip-bot2 for Ricardo Neri wrote:
> +#define X86_HYBRID_CPU_TYPE_ID_SHIFT	24
> +
> +/**
> + * get_this_hybrid_cpu_type() - Get the type of this hybrid CPU
> + *
> + * Returns the CPU type [31:24] (i.e., Atom or Core) of a CPU in
> + * a hybrid processor. If the processor is not hybrid, returns 0.
> + */
> +u8 get_this_hybrid_cpu_type(void)
> +{
> +	if (!cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
> +		return 0;
> +
> +	return cpuid_eax(0x0000001a) >> X86_HYBRID_CPU_TYPE_ID_SHIFT;
> +}

Hi Folks,

Sorry to dredge up an old thread.  But, where does this information
about "If the processor is not hybrid, returns 0." come from?

What is there to keep cpuid_eax(0x0000001a) from having 0x0 in those
bits?  Seems to me like 0 is theoretically a valid hybrid CPU type.  Right?

  reply	other threads:[~2023-05-05 16:42 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-12 14:30 [PATCH V6 00/25] Add Alder Lake support for perf (kernel) kan.liang
2021-04-12 14:30 ` [PATCH V6 01/25] x86/cpufeatures: Enumerate Intel Hybrid Technology feature bit kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Ricardo Neri
2021-04-12 14:30 ` [PATCH V6 02/25] x86/cpu: Add helper function to get the type of the current hybrid CPU kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Ricardo Neri
2023-05-05 16:42     ` Dave Hansen [this message]
2023-05-10 18:18       ` Ricardo Neri
2023-05-10 18:33         ` Dave Hansen
2023-05-10 19:15           ` Luck, Tony
2023-05-10 23:56           ` Ricardo Neri
2021-04-12 14:30 ` [PATCH V6 03/25] perf/x86: Track pmu in per-CPU cpu_hw_events kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 04/25] perf/x86/intel: Hybrid PMU support for perf capabilities kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 05/25] perf/x86: Hybrid PMU support for intel_ctrl kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 06/25] perf/x86: Hybrid PMU support for counters kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 07/25] perf/x86: Hybrid PMU support for unconstrained kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 08/25] perf/x86: Hybrid PMU support for hardware cache event kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 09/25] perf/x86: Hybrid PMU support for event constraints kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 10/25] perf/x86: Hybrid PMU support for extra_regs kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 11/25] perf/x86/intel: Factor out intel_pmu_check_num_counters kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 12/25] perf/x86/intel: Factor out intel_pmu_check_event_constraints kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 13/25] perf/x86/intel: Factor out intel_pmu_check_extra_regs kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 14/25] perf/x86: Remove temporary pmu assignment in event_init kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 15/25] perf/x86: Factor out x86_pmu_show_pmu_cap kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 16/25] perf/x86: Register hybrid PMUs kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 17/25] perf/x86: Add structures for the attributes of Hybrid PMUs kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 18/25] perf/x86/intel: Add attr_update for " kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:30 ` [PATCH V6 19/25] perf/x86: Support filter_match callback kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 20/25] perf/x86/intel: Add Alder Lake Hybrid support kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 21/25] perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 22/25] perf/x86/intel/uncore: Add Alder Lake support kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 23/25] perf/x86/msr: Add Alder Lake CPU support kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 24/25] perf/x86/cstate: " kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Kan Liang
2021-04-12 14:31 ` [PATCH V6 25/25] perf/x86/rapl: Add support for Intel Alder Lake kan.liang
2021-04-20 10:46   ` [tip: perf/core] " tip-bot2 for Zhang Rui

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