Messages in this thread | | | Date | Tue, 9 Jun 2015 11:05:43 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 2/4] x86, mwaitt: make delay method configurable |
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On Tue, Jun 09, 2015 at 11:13:39AM +0800, Huang Rui wrote: > This patch introduces a kernel parameter (delay), user is able to configure > it at boot loader to choose different types of delay method. > > Default schema is to use TSC delay. This update can be more flexiable to > add new delay method. > > Suggested-by: Suravee Suthikulanit <suravee.suthikulpanit@amd.com> > Signed-off-by: Huang Rui <ray.huang@amd.com> > --- > arch/x86/include/asm/delay.h | 7 +++++++ > arch/x86/kernel/setup.c | 19 +++++++++++++++++++ > arch/x86/lib/delay.c | 12 +++++++++++- > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/delay.h b/arch/x86/include/asm/delay.h > index 9b3b4f2..99873ec 100644 > --- a/arch/x86/include/asm/delay.h > +++ b/arch/x86/include/asm/delay.h > @@ -5,4 +5,11 @@ > > void use_tsc_delay(void); > > +extern unsigned long boot_option_delay; > + > +enum delay_type { > + DELAY_LOOP=0, > + DELAY_TSC, > +}; > + > #endif /* _ASM_X86_DELAY_H */ > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 0b10698..cc2886d 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -111,6 +111,7 @@ > #include <asm/mce.h> > #include <asm/alternative.h> > #include <asm/prom.h> > +#include <asm/delay.h> > > /* > * max_low_pfn_mapped: highest direct mapped pfn under 4GB > @@ -844,6 +845,24 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) > return 0; > } > > +static int __init delay_setup(char *str) > +{ > + if (!str) > + return -EINVAL; > + > + if (!strcmp(str, "tsc")) { > + pr_info("using tsc delay\n"); > + boot_option_delay = DELAY_TSC; > + } else if (!strcmp(str, "loop")) { > + pr_info("using loop delay\n"); > + boot_option_delay = DELAY_LOOP; > + } else > + return -1;
What Peter said.
And we did talk about this already in the last review. You guys want to drop all those kernel parameters and use MWAITX delay by default when:
1. HW supports MWAITX
*and*
2. delay fits in u32.
Kernel parameters is a bad bad idea.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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