Hi, On 05/25/2017 12:56 AM, Jan Kiszka wrote: > On 2017-03-21 13:19, tip-bot for Lu Baolu wrote: >> Commit-ID: dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b >> Gitweb: >> http://git.kernel.org/tip/dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b >> Author: Lu Baolu <[email protected]> >> AuthorDate: Tue, 21 Mar 2017 16:01:29 +0800 >> Committer: Ingo Molnar <[email protected]> >> CommitDate: Tue, 21 Mar 2017 12:28:45 +0100 >> >> x86/timers: Add simple udelay calibration >> >> Add a simple udelay calibration in x86 architecture-specific >> boot-time initializations. This will get a workable estimate >> for loops_per_jiffy. Hence, udelay() could be used after this >> initialization. >> >> Signed-off-by: Lu Baolu <[email protected]> >> Acked-by: Thomas Gleixner <[email protected]> >> Cc: Andy Lutomirski <[email protected]> >> Cc: Borislav Petkov <[email protected]> >> Cc: Brian Gerst <[email protected]> >> Cc: Denys Vlasenko <[email protected]> >> Cc: Greg Kroah-Hartman <[email protected]> >> Cc: H. Peter Anvin <[email protected]> >> Cc: Josh Poimboeuf <[email protected]> >> Cc: Linus Torvalds <[email protected]> >> Cc: Mathias Nyman <[email protected]> >> Cc: Peter Zijlstra <[email protected]> >> Cc: [email protected] >> Link: >> http://lkml.kernel.org/r/[email protected] >> Signed-off-by: Ingo Molnar <[email protected]> >> --- >> arch/x86/kernel/setup.c | 22 ++++++++++++++++++++++ >> 1 file changed, 22 insertions(+) >> >> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c >> index 4bf0c89..e70204e 100644 >> --- a/arch/x86/kernel/setup.c >> +++ b/arch/x86/kernel/setup.c >> @@ -837,6 +837,26 @@ dump_kernel_offset(struct notifier_block *self, >> unsigned long v, void *p) >> return 0; >> } >> >> +static void __init simple_udelay_calibration(void) >> +{ >> + unsigned int tsc_khz, cpu_khz; >> + unsigned long lpj; >> + >> + if (!boot_cpu_has(X86_FEATURE_TSC)) >> + return; >> + >> + cpu_khz = x86_platform.calibrate_cpu(); >> + tsc_khz = x86_platform.calibrate_tsc(); >> + >> + tsc_khz = tsc_khz ? : cpu_khz; >> + if (!tsc_khz) >> + return; >> + >> + lpj = tsc_khz * 1000; >> + do_div(lpj, HZ); >> + loops_per_jiffy = lpj; >> +} >> + >> /* >> * Determine if we were loaded by an EFI loader. If so, then we have also >> been >> * passed the efi memmap, systab, etc., so we should use these data >> structures >> @@ -985,6 +1005,8 @@ void __init setup_arch(char **cmdline_p) >> */ >> x86_configure_nx(); >> >> + simple_udelay_calibration(); >> + >> parse_early_param(); >> >> #ifdef CONFIG_MEMORY_HOTPLUG >> > Can we move this past init_hypervisor_platform()?
Yes, we can as far as I can see. Best regards, Lu Baolu > Otherwise, the > x86_platform hooks aren't fully initialized yet, and we may use the > wrong functions. > > Jan >
