Re: [PATCH RFC] Send checkpoint and restart debug info to a log file (v2)

[Oren Laadan <orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org>]

Matt Helsley wrote:
> On Wed, Oct 21, 2009 at 07:51:57PM -0500, Serge E. Hallyn wrote:
>> Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org):
> 
> <snip>
> 
>>>> More practically, requiring userspace to pass over a flag
>>>> consisting of CKPT_DBG_MEM|CKPT_DBG|FILE|CKPT_DBG|TASK, and
>>>> handle corresponding usage flags, is not nice.
>>> I agree with you on about this. Maybe we want a better
>>> interface ?
>>>
>>> Which brings me to this random thought: maybe we want to
>>> make the fourth argument of sys_{checkpoint,restart} a
>>> structure, to make it easier to extend it in the future
>>> without having to go throw a clone3-like hell...
> 
> Adding new kernel interfaces is supposed to be somewhat hellish.
> 
>>> Specifically, this structure could now be:
>>>
>>> struct ckpt_args {
>>> 	int version;
>>> 	int logfd;
>>> 	int logmask;
>>> };
>>>
>>> (or use union checkpoint {} and union restart {} to tell
>>> between checkpoint- and restart-related args.
>> Well I don't like passing structs to the kernel actually (and
> 
> Let's not do this. I agree that passing structs, when unnecessary,
> is gross. Especially if it gets used to extend the arguments
> passed via the syscall interface (new flag values I don't mind).

Ok, we already allow future extension by being strict about
which flags are taken or not.

Then what do we do with logmask ?   I prefer it to be a per-syscall
value as opposed to a system-wise setting.

Oren.