Messages in this thread | | | Date | Tue, 29 Jul 2008 07:33:52 -0700 | From | Mike Travis <> | Subject | Re: linux-next: build failure |
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Mike Travis wrote: > Ingo Molnar wrote: >> * KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> >>>> * Stephen Rothwell <sfr@canb.auug.org.au> wrote: >>>> >>>>> Hi Ingo, >>>>> >>>>> On Tue, 29 Jul 2008 10:00:55 +0200 Ingo Molnar <mingo@elte.hu> wrote: >>>>>>> -#define cpumask_of_cpu(cpu) ({ *get_cpu_mask(cpu); }) >>>>>>> +#define cpumask_of_cpu(cpu) (*get_cpu_mask(cpu)) >>>>>> hm, i'm wondering - is this a compiler bug? >>>>> Or maybe a deficiency in such an old compiler (v3.4.5) but the fix >>>>> makes sense anyway, right? >>>> yeah, i was just wondering. >>> in linux/README >>> >>> COMPILING the kernel: >>> >>> - Make sure you have at least gcc 3.2 available. >>> For more information, refer to Documentation/Changes. >>> >>> So, if 3.4.5 is old, Should we change readme? >> the fix is simple enough. >> >> but the question is, wont it generate huge artificial stackframes with >> CONFIG_MAXSMP and NR_CPUS=4096? Maybe it is unable to figure out and >> simplify the arithmetics there - or something like that. >> >> Ingo > > I've looked at stack frames quite extensively and usually they are > not generated unless you explicitly use a named cpumask variable, > pass a cpumask by value, expect a cpumask function return, create > an initializer that contains a cpumask field, and (probably a couple > more I missed). > > Almost all others are done efficiently via pointers or simple > struct copies: > > cpus_xxx(*cpumask_of_cpu(), ... > struct->cpumask_var = *cpumask_of_cpu() > global_cpumask_var = *cpumask_of_cpu() > etc. > > Thanks, > Mike
Geez, I edited the above after I first used *cpumask_var and didn't get the semantics right!
cpus_xxx(cpumask_of_cpu(), ... struct->cpumask_var = cpumask_of_cpu() global_cpumask_var = cpumask_of_cpu()
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