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From: | Bijan Mottahedeh |
Subject: | Re: [Qemu-devel] [RFC QEMU 1/2] arm/virt: Initialize generic timer scale factor dynamically |
Date: | Fri, 9 Nov 2018 19:12:08 -0800 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 11/8/2018 6:21 AM, Richard Henderson wrote:
Is it ok to ifdef the asm statement with CONFIG_KVM, or what would be the correct way to account for TCG vs. KVM?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~
Thanks. --bijan
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