On Tue 2018-07-31 11:11:53, David Howells wrote: > Pavel Machek <pavel@xxxxxx> wrote: > > > Proposal is "message %s foo %s\0param 1\0param2\0", only strings > > allowed. > > I think that's too strict and you will need to allow integer values, IP > addresses and possibly other things also. It could certainly have a limited > set (e.g. no kernel pointers). I'd always use strings at kernel->user interface. Yes, we should support integers and IP addresses in kernel, but I'd convert them to strings before passing them to userspace. > You also haven't proposed what you think the internal interface should look > like. No, I did not. > and then the kernel has to render the whole lot into > > Another example, in ext4 we have: > > printk(KERN_NOTICE "EXT4-fs (%s): last error at time %u: %.*s:%d", > > so we could do something like: > > infof(fc, "EXT4-fs (%s): last error at time %u: %.*s:%d", ...); > > on mount. But the use of "%.*s" is a pain for your interface. We can't pass > qualifiers like "*" to userspace, so either the caller would have to copy the > string first or the logging routines would have to edit the format string. > Though I suppose we could leave the editing to userspace. I guess internal interface can stay the same, at expense of complexity in infof function. It would data according to %blablax into string, then replace %blablax with %s. I guess we can keep infof function simpler by only allowing certain format specifiers... Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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