Re: [Vserver] Re: [parisc-linux] syscall number for vserver

[Herbert Poetzl <herbert@13thfloor.at>]

On Thu, Dec 18, 2003 at 08:25:06AM +0100, Christoph Hellwig wrote:
> On Wed, Dec 17, 2003 at 11:16:18PM +0100, Herbert Poetzl wrote:
> > 
> > Hi everyone!
> > 
> > I would like to 'officially' reserve a syscall number
> > for parisc(64)/vserver ... 
> 
> The syscall is the typical multiplexer crap, so an actual submission
> wouldn't have any chance.  Please fix up your junk beofe trying to
> play the reserve a syscall scheme.  This didn't work for afs or
> LSM either.

hohoho!

you are a funny guy, and I'm sure you will
explain your statement in all detail ...

just for your information:

vserver folks really do not care whether or not the
syscall is reserved on their architecture, as long 
as it's there, and it will be there anyway, I just 
wanted to be polite and correct, so if you 'think'
we split up the switch just for parisc(64) again, 
then I can assure you, that just won't happen ...

best,
Herbert

PS:

if you are actually interrested _how_ this is done
and _what_ we do to minimize issues, have a look at

 http://vserver.13thfloor.at/Stuff/vswitch.h
 http://vserver.13thfloor.at/Stuff/vswitch.c

some facts:

- the project started with 2 syscalls, and has grown
  to 7-8 syscalls (depending on the version)

- the syscall switch was not my idea, but I have to
  admit, that it simplified development drastically
  (no need to ask 10 people for a new syscall ;)

- we _are_ supporting several different architectures
  and we _are_ trying to avoid issues where possible,
  (for example we use the c99 types for structs)
  
- userspace handles this with a versioned interface


On Sun, Aug 31, 2003 at 10:57:42AM -0400, Rik van Riel wrote:
> How about a sys_vserver multiplexer so we can easily add
> things like setting a new ipv6 root to the interface,
> without needing yet another syscall ?

On Sat, Oct 04, 2003 at 03:31:11PM -0700, David S. Miller wrote:
>>> This interface stinks, system calls should have fixed known types not
>>> depending upon the value of some parameter, anything else is a
>>> disaster waiting to happen ala ioctl().

>> but I have to say, that I see no advantage in
>> using more syscalls, if they have to pass a user
>> space struct anyway ... (not all do)

> Then have a fixed enumeration for the command, and pass in
> as the type argument a union of the various possible structures.
> Then the types are clearly defined and it's much easier to write
> the compat translation layer.

On Sat, Oct 04, 2003 at 04:57:58PM -0700, David S. Miller wrote:
>>> We have like 7 or 8 system calls for posix timers,
>>> so I don't see why we can't have 3 or 4 for vserver
>>> so that we can have a well defined type get passed in
>>> for each specific system call.

>> that was my saying in the first place, please  
>> advise how to proceed on that?
>> (am I running in circles?)

> Ok, I already sent off an email to Linus so that I can have
> a discussion with him about this first.  I'll reply again once
> he replies to me and we discuss things.