Messages in this thread | | | Date | Thu, 30 Aug 2012 15:17:48 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH RFC] x86/mce: Move MCE sysfs attributes out of the per-cpu location |
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On 08/29/2012 08:13 PM, Luck, Tony wrote: >> Note: I'm not sure if it's ok to change sysfs entries and this does break >> userspace tools that depend on the current path for some of these attributes. >> So, they will need to be updated to use the new path. However, if we ever get >> to a point where cpu0 can be offlined, these tools will need to be updated >> anyway (as they mostly hardcode machinecheck0 currently) > > Linus' clarified his "never break user space" edict at the kernel summit > on Monday. Paraphrasing: > > If nobody notices, or nobody complains, then we can make changes. But > if anyone does complain, then the patch gets reverted. > > So if you want to do this, the right approach would be to change the > utilities that use this to look in the new location for these sysfs files > first, and fall back to looking in the old per-cpu place. > > Next (or in parallel) have the kernel provide both interfaces. > > Wait a long[1] time so that most people have updated utilities. > > Delete the per-cpu interfaces from the kernel. > > Delete the per-cpu references from the utilities. > > -Tony > > [1] Long enough that there are no complaints. At least a year, probably two or more. >
Makes sense. Thanks for the explanation. I will send a new patch for this.
Thanks, Naveen
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