Messages in this thread | | | Date | Wed, 13 Dec 2000 23:57:27 -0500 (EST) | From | Alexander Viro <> | Subject | Re: CORBA vs 9P |
| |
On Wed, 13 Dec 2000, Chris Lattner wrote:
> > > Okay, so there are _stubs_ for these platforms. How many languages are > > > there bindings for? > > Grr... Let's define the terms, OK? What is available: kernel code that > > represents the client side of RPC as a filesystem. Userland clients do > > not know (or care) about the mechanisms involved. > > But they DO CARE about the format of the data.
And how would CORBA help here? Because format changes are usually coming from the _contents_ changes. And if you don't care about the contents - why the hell do you retrieve the object int the first place?
> > And files with structure are things of dreadful past. BTDT. > > You really need to... work with an OS that would have and enforce > > "structured files" <spit> to appreciate the beauty of ASCII streams. > > Ahhh, so ASCII streams are a wonderful thing. Are you an XML fan? :)
No, thanks.
> > However, that's a different story. What I _really_ don't understand > > is the need to export anything structured from kernel to userland. > > Okay, how about a few examples. How about /proc/meminfo? How about the > "stat" structure? How about /proc/stat? You seem to be indicating that > ASCII files are fine for general exportation of kernel information. The
Yes, _if_ you take care to think what you are exporting. /proc/meminfo is a shi..ning example of _not_ doing that over many years.
> /proc filesystem begs to differ. One specific example is the > /proc/meminfo file. Why is it that one field is 0 now? Ouch we can't > change the format of the file because we'll break some program. Crap, you > want to add a field, well, tough luck.
Oh, cool. So CORBA would magically change the definition of the structure in your (C/Modula-3/APL/COBOL) programs. How? And what would happen with the code that used to access the field in question?
> The struct stat example is one _trivial_ example of "the need to export > anything structured from kernel to userland".
It's a trivial example of "why you need to think before deciding what to export".
> > IOW, I would really like to see a description of use of your > > mechanism. If it's something along the lines of "let's take a network > > card driver, implement it in userland and preserve the current API" - > > see the comment about layering violations. You've taken an internal ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > API and exposed it to userland in all gory details. See also your own > > comment about internal APIs being not convenient for such operations. > > I'm not trying to dictate interfaces. I'm not trying to tell people what > to use this stuff for. I'm arguing that it's useful and that you can do > very interesting things with it.
And when interface changes, you do what, exactly?
> > If it's something else - I wonder what kind of objects you are talking > > about and why opaque stuff (== file descriptors) would not be sufficient. > > Opaque stuff is fine. I have no problem with file descriptors. They > effectively solve the exact same class of problems that CORBA does, except > that they add significant _API BLOAT_ because every little "method" that > implements them gets a syscall.
Huh? Could you elaborate, please?
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
| |