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Re: What do you wish for in an package manager?

On Fri, Dec 29, 2000 at 11:47:44PM +0000, Mark Seaborn wrote:
> They are unrelated if they do not need to communicate (as an
> example).  If they do not need to communicate, they may as well run on 
> different machines, in which case they can use different versions of
> libc.  But I want to be able to merge those two machines into one --
> this is what a multi-user system is all about -- and have the two
> programs continue to use different libcs.

	s/libc/kernel/ and you have a big problem. Use
	plex86, VMware or an IBM mainframe. Or a pile of
	inexpensive PCs (but hey, you already had that!
	How nice!)

> As I suggested before, it would be easy if different processes could
> have different views on the filesystem.  This is feasible on the
> Hurd.  Linux is not as flexible, unfortunately.  I can envisage

	You are not up to date; Al Viro has been a busy boy.
	Expect process namespaces in 2.5; maybe even as an
	additional patches in 2.4.x (x>=1). Most of the
	groundwork is already there.

	Or look at ClusterNFS. Or any of the zillion hacks that
	do something similar, with varying levels of success.

> modifying libc so that it is possible to redirect files elsewhere on a 
> per-process basis (ideally this would be done in a general manner so
> that a call to open() could be forwarded to a server in another
> process, which would then pass back opened fd).

	libc ain't enough, really. You'd need to trick the 
	syscalls, too. For what you describe above, modifying
	libc sounds just like extra work. LD_PRELOAD, perhaps.

	But the real solution is a kernel-based one. And it's already
	designed and waiting for someone like Al Viro to have a month
	off. Anyone want to pay him a month worth of salary?-)

> (I'm very interested in user filesystems in general.  I played with
> perlfs last year, but it was too unreliable, and it broke when I
> upgraded perl anyway.  Modifying libc now seems the way to go, but I'm 
> not prepared to hack libc on this level yet.)

	My current collection of resources is at


	(but that doesn't include most of the stacking material;
	I haven't organized it yet)

Perl poetry: for ($tv) { s/blood/caffeine/ while /blood/ }

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