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Re: [Qemu-devel] [RFC QEMU 1/2] arm/virt: Initialize generic timer scale
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-devel] [RFC QEMU 1/2] arm/virt: Initialize generic timer scale factor dynamically |
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Date: |
Thu, 8 Nov 2018 15:21:47 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 |
On 11/7/18 7:48 PM, Bijan Mottahedeh wrote:
>
> +static void set_system_clock_scale(void)
> +{
> + unsigned long cntfrq_el0;
> +
> + asm volatile("mrs %0, cntfrq_el0" : "=r"(cntfrq_el0));
> +
> + if (cntfrq_el0 == 0) {
> + cntfrq_el0 = GTIMER_SCALE_DEF;
> + }
> +
> + system_clock_scale = NANOSECONDS_PER_SECOND / (int)cntfrq_el0;
> +}
This only works for kvm.
For TCG you need to use the default always. In particular, it won't even
compile for an x86 host.
r~