On 4/29/21 2:08 PM, Song Bao Hua (Barry Song) wrote: >> Do we think >PAGE_SIZE data out of a sysfs file is a worse ABI break or >> something? > This kind of cpu list ABIs have been there for many years but have > never been documented well. > > We have two ABIs: > xxx_cpus - in format like 3333333333 > xxx_cpus_list - in format like 0,3,5,7,9,11,13.... > > xxx_cpus_list is another human-readable version of xxx_cpus. It doesn't > include any more useful information than xxx_cpus. > > xxx_cpus won't overflow based on BUILD_BUG_ON and maximum NR_CPUS > in kconfig nowadays. > > if people all agree the trimmed list is a break of ABI, I think we may > totally remove this list. For these days, this list probably has never > overflowed but literally this could happen. > > thoughts? >From what Greg said, it sounds like removing the BUILD_BUG_ON(), making it a binary sysfs file, and making it support arbitrary lengths is the way to go.
