Re: Adding checkpointing API to Linux kernel

Richard B. Johnson (root@chaos.analogic.com)
Mon, 25 Jan 1999 08:47:59 -0500 (EST)


On Sat, 23 Jan 1999, Olaf Titz wrote:

> > PS: How many things would break if we forced ioctls to _always_ pass
> >
> > struct foo {
> > int len;
> > char data[len];
> > } ?
>
> At the user level, everything would break. ;-) But perhaps it would be
> possible to redefine just the ioctl syscall (to take an additional
> length parameter, perhaps) and let the library sort it out? This way
> user programs would remain compatible.
>
> Olaf
>

It "would have been" ideal if the original ioctl() parameter passing
was done like this. DEC called it a $DESCRIPTOR. Every sys-call had
a length, followed by a type, followed by whatever...

However, since we emulate Unix, to do this thing at this late date
means that the length of every one of those structures has to be known
to the C library interface. This may not be Good(tm).

Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.1.131 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.
Wisdom : It's not a Y2K problem. It's a Y2Day problem.

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