Re: [PATCH 1/2] CPU, NUMA topology ABIs: clarify the overflow issue of sysfs pagebuf

[gregkh@xxxxxxxxxxxxxxxxxxx]

On Thu, Apr 29, 2021 at 03:38:39PM -0700, Dave Hansen wrote:
> On 4/29/21 3:32 PM, Song Bao Hua (Barry Song) wrote:
> > $ strace numactl --hardware  2>&1 | grep cpu
> > openat(AT_FDCWD, "/sys/devices/system/cpu",
> > O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3
> > openat(AT_FDCWD, "/sys/devices/system/node/node0/cpumap", O_RDONLY) = 3
> > openat(AT_FDCWD, "/sys/devices/system/node/node1/cpumap", O_RDONLY) = 3
> > openat(AT_FDCWD, "/sys/devices/system/node/node2/cpumap", O_RDONLY) = 3
> > openat(AT_FDCWD, "/sys/devices/system/node/node3/cpumap", O_RDONLY) = 3
> > 
> > If we move to binary, it means we have to change those applications.
> 
> I thought Greg was saying to using a sysfs binary attribute using
> something like like sysfs_create_bin_file().  Those don't have the
> PAGE_SIZE limitation.  But, there's also nothing to keep us from spewing
> nice human-readable text via the "binary" file.

That is correct.