Messages in this thread | | | Subject | RE: [PATCH v2:3/3]Export cpu topology by sysfs | Date | Mon, 26 Dec 2005 15:38:16 +0800 | From | "Zhang, Yanmin" <> |
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>>-----Original Message----- >>From: Greg KH [mailto:greg@kroah.com] >>Sent: 2005年12月24日 3:16 >>To: Zhang, Yanmin >>Cc: Yanmin Zhang; linux-kernel@vger.kernel.org; discuss@x86-64.org; linux-ia64@vger.kernel.org; Siddha, Suresh B; Shah, Rajesh; >>Pallipadi, Venkatesh >>Subject: Re: [PATCH v2:3/3]Export cpu topology by sysfs >> >>On Fri, Dec 23, 2005 at 12:03:27PM +0800, Zhang, Yanmin wrote: >>> >>Can't you just use an attribute group and attach it to the cpu kobject? >>> >>That would save an array of kobjects I think. >>> As you know, current i386/x86_64 arch also export cache info under >>> /sys/device/system/cpu/cpuX/cache. Is it clearer to export topology >>> under a new directory than under cpu directly? >> >>No, the place in the sysfs tree you are putting this is just fine. I'm >>just saying that you do not need to create a new kobject for these >>attributes. Just use an attribute group, and you will get the same >>naming, without the need for an extra kobject (and the whole array of >>kobjects) at all. >> >>Does that make more sense? Yes, indeed. Now, I used your idea and the patch became simpler. Thanks.
>> >>> >>> +static int __cpuinit topology_cpu_callback(struct notifier_block *nfb, >>> >>> + unsigned long action, void *hcpu) >>> >>> +{ >>> >>> + unsigned int cpu = (unsigned long)hcpu; >>> >>> + struct sys_device *sys_dev; >>> >>> + >>> >>> + sys_dev = get_cpu_sysdev(cpu); >>> >>> + switch (action) { >>> >>> + case CPU_ONLINE: >>> >>> + topology_add_dev(sys_dev); >>> >>> + break; >>> >>> +#ifdef CONFIG_HOTPLUG_CPU >>> >>> + case CPU_DEAD: >>> >>> + topology_remove_dev(sys_dev); >>> >>> + break; >>> >>> +#endif >>> >> >>> >>Why ifdef? Isn't it safe to just always have this in? >>> If no ifdef here, gcc reported a compiling warning when I compiled it >>> on IA64 with CONFIG_HOTPLUG_CPU=n. >> >>Then you should probably go change it so that CPU_DEAD is defined on >>non-smp builds, otherwise the code gets quite messy like the above :)
Sorry. My previous explanation is confusing. It's a link warning on ia64. On ia64, the kernel vmlinux doesn't include section .exit.text, so ld will report a link warning when a function is in section .exit.text and another function (not in .exit.text) calls the first one. When CONFIG_HOTPLUG_CPU=n, function topology_remove_dev is in section .exit.text, but its caller topology_remove_dev is not in .exit.text.
i386 and x86_64 kernel vmlinux does include .exit.text and discard it only when running, so there is no such warning on i386/x86_64.
There is no other better approach to get rid of the warning unless we change arch/ia64/kernel/vmlinux.lds.S to keep all .exit.text in kernel image.
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