Date: Thu, 12 Sep 2019 23:38:53 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 240475] [PATCH]: Add support for CPUID 0x16 in tsc_freq_cpuid() (TSC clock) Message-ID: <bug-240475-227-Npc6A4fcyA@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-240475-227@https.bugs.freebsd.org/bugzilla/> References: <bug-240475-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=240475 --- Comment #7 from Neel Chauhan <neel@neelc.org> --- It's true that Linux does this (lines 660-661): crystal_khz = eax_base_mhz * 1000 * eax_denominator / ebx_numerator; But in the same function, Linux returns this (line 674): return crystal_khz * ebx_numerator / eax_denominator; So the numerator and denominator in crystal_khz effectively cancels out on CPUID 0x16. >From what I understand, Linux expects the value in kilohertz, so a multiplier of 1000 works on Linux. I believe FreeBSD expects hertz, so a multiplier of 1000000 is needed. For unit conversion of megahertz to hertz, 1000 Hz = 1 KHz and 1000 KHz = 1 MHz, so 1 MHz = 1000 KHz * 1000 Hz. Also, using the numerator and denominator wouldn't work (I've tried that, I got a kernel panic). -- You are receiving this mail because: You are the assignee for the bug.help
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