Re: How about adding a name for bpftool self created maps?

[Hangbin Liu <liuhangbin@gmail.com>]

On Tue, Jun 21, 2022 at 10:28:27PM +0100, Quentin Monnet wrote:
> > When I using `bpftool map list` to show what maps user using. bpftool will
> > show maps including self created maps. Apart from the "pid_iter.rodata",
> > there are also array maps without name, which makes it hard to filter out
> > what maps user using. e.g.
> >
> > # bpftool map list
> > 63: array  flags 0x0
> >          key 4B  value 32B  max_entries 1  memlock 4096B
> > 65: array  name pid_iter.rodata  flags 0x480
> >          key 4B  value 4B  max_entries 1  memlock 4096B
> >          btf_id 98  frozen
> >          pids bpftool(10572)
> > 66: array  flags 0x0
> >          key 4B  value 32B  max_entries 1  memlock 4096B
> >
> > So do you have plan to add a special name for the bpftool self created maps?
> > Or do you know if there is a way to filter out these maps?
> 
> Hi Hangbin,
> 
> No plan currently. Adding names has been suggested before, but it's
> not compatible with some older kernels that don't support map names
> [0]. Maybe one solution would be to probe the kernel for map name
> support, and to add a name if supported.

Hi Quentin,

Thanks for the reply. Probe the kernel and add name if supported makes
sense to me.

Thanks
Hangbin

> 
> Other than this I'm not aware of a reliable way to filter out these
> maps at the moment. This could probably be done in bpftool since we
> should have the ids of the self-generated maps. But I think I'd rather
> find a way to add map names, if possible. It would make it easier to
> recognise/filter these maps on regular listing, whereas a new option
> would be harder for users to discover.
> 
> Quentin
> 
> [0] https://lore.kernel.org/bpf/CAEf4BzY66WPKQbDe74AKZ6nFtZjq5e+G3Ji2egcVytB9R6_sGQ@mail.gmail.com/