Re: [PATCH v5 27/29] fs/resctrl: Add file system mechanism for architecture info file

["Luck, Tony" <tony.luck@intel.com>]

On Tue, Jun 03, 2025 at 09:15:02PM -0700, Reinette Chatre wrote:
> Hi Tony,
> 
> On 5/21/25 3:50 PM, Tony Luck wrote:
> > Creation of all files in the resctrl file system is under control of
> > the file system layer.
> > 
> > But some resources may need to add a file to the info/{resource}
> > directory for debug purposes.
> > 
> > Add a new rdt_resource::info_file field for the resource to specify
> > show() and/or write() operations. These will be called with the
> > rdtgroup_mutex held.
> > 
> > Architecture can note the file is only for debug using by setting
> > the rftype::flags RFTYPE_DEBUG bit.
> 
> This needs to change. This punches a crater through the separation
> between fs and arch that we worked hard to achieve. Please make an attempt
> to do so as I am sure you can.

The file I want to create here amy only be of interest in debugging
the telemetry h/w interface. So my next choice is debugfs.

But creation of the debugfs "resctrl" directory is done by file
system code and the debugfs_resctrl variable is only marked "extern" by
fs/resctrl/internal.h, so currently not accessible to architecture code.

Is that a deliberate choice? Would it be OK to make that visible to
architecture code to create files in /sys/kernel/debug/resctrl?

Or should I add my file in a new /sys/kernel/debug/x86/resctrl
directory?

-Tony