Messages in this thread | | | Date | Wed, 17 Jun 2009 14:46:05 -0700 | From | Linda Walsh <> | Subject | IGNORE: Re: non-standard config in my running distro Default kernel: Effect? |
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Please ignore this non-issue. I should have sorted my compare files. (Sigh)...
Linda Walsh wrote: > > I found what appears to be a "non-standard configuration" in a > distro's "Default-SMP", non-Xen kernel, where /proc/config.gz > from the running kernel has (I only ran into this doing a diff between > a manually constructed config and my running kernel): > > CONFIG_X86_SMP=y > CONFIG_X86_64_SMP=y > > But does NOT have: > > CONFIG_USE_GENERIC_SMP_HELPERS=y > > From what I can tell, this shouldn't be a possible configuration, since > CONFIG_X86_SMP should force it to be set to 'y' (not unset). > > Would this config, (SMP='y', generic_smp_helpers=(undef) ) have any > odd effects? Is there a specific "effect" or "feature" one gets > by having 'smp=y' but not having the smp_helpers enabled? > > In my x86_64 arch, the places I see it tested are: > > block/blk-softirq.c: > #if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS) > #else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */ > block/blk-sysfs.c: > #if defined(CONFIG_USE_GENERIC_SMP_HELPERS) > include/linux/smp.h: > #ifdef CONFIG_USE_GENERIC_SMP_HELPERS > /kernel/Kconfig.hz: > def_bool HIGH_RES_TIMERS && (!SMP || USE_GENERIC_SMP_HELPERS) > kernel/softirq.c: > #ifdef CONFIG_USE_GENERIC_SMP_HELPERS > #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ > > --- > It appears it may disable some softirq routines. > > In include/linux/smp.h, having it undefined would disable the > definition of the functions: > generic_smp_call_function_single_interrupt, > generic_smp_call_function_interrupt, > ipi_call_lock, ipi_call_unlock, > ipi_call_lock_irq & ipi_call_unlock_irq > > Does this have any performance or integrity (lost interrupt) > implications? > > > > > > > > > > > >
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