Re: [PATCH] x86: printk_time to use tsc before cpu_clock is ready

Peter Zijlstra
2008-07-29T10:13:36Z

On Tue, 2008-07-29 at 03:09 -0700, Yinghai Lu wrote:
> so can get tsc value on printk
>
> need to apply after
> [PATCH] printk_time: prepare stub for using other than cpu_clock

You failed to mention why we want this... ;-)

> Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
>
> ---
> arch/x86/kernel/cpu/common.c | 11 +++++++++++
> arch/x86/kernel/cpu/common_64.c | 12 ++++++++++++
> 2 files changed, 23 insertions(+)
>
> Index: linux-2.6/arch/x86/kernel/cpu/common.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/cpu/common.c
> +++ linux-2.6/arch/x86/kernel/cpu/common.c
> @@ -617,6 +617,15 @@ __setup("clearcpuid=", setup_disablecpui
>
> cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;
>
> +static unsigned long long tsc_clock(int cpu)
> +{
> + unsigned long long t;
> +
> + rdtscll(t);
> +
> + return t;
> +}
> +
> void __init early_cpu_init(void)
> {
> struct cpu_vendor_dev *cvdev;
> @@ -627,6 +636,8 @@ void __init early_cpu_init(void)
> cpu_devs[cvdev->vendor] = cvdev->cpu_dev;
>
> early_cpu_detect();
> + if (cpu_has_tsc)
> + set_printk_time_clock(tsc_clock);
> validate_pat_support(&boot_cpu_data);
> }
>
> Index: linux-2.6/arch/x86/kernel/cpu/common_64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/cpu/common_64.c
> +++ linux-2.6/arch/x86/kernel/cpu/common_64.c
> @@ -215,6 +215,15 @@ static void __init early_cpu_support_pri
> }
> }
>
> +static unsigned long long tsc_clock(int cpu)
> +{
> + unsigned long long t;
> +
> + rdtscll(t);
> +
> + return t;
> +}
> +
> static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c);
>
> void __init early_cpu_init(void)
> @@ -227,6 +236,9 @@ void __init early_cpu_init(void)
> cpu_devs[cvdev->vendor] = cvdev->cpu_dev;
> early_cpu_support_print();
> early_identify_cpu(&boot_cpu_data);
> +
> + if (cpu_has_tsc)
> + set_printk_time_clock(tsc_clock);
> }
>
> /* Do some early cpuid on the boot CPU to get some parameter that are
> --
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