DragonFly BSD
DragonFly bugs List (threaded) for 2006-04
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Re: well, duh, I guess ;) (was Re: odd linuxulator problem with linux TLS ...)

To: David Cuthbert <dacut@xxxxxxxxx>
From: Andrew Atrens <atrens@xxxxxxxxxxxxxxxxxx>
Date: Thu, 20 Apr 2006 08:32:03 -0400

David Cuthbert wrote:
> Andrew Atrens wrote:
>> seems the linuxulator is picking up libc.so.6 from /usr/lib instead of
>> from
>> /compat/linux/lib .. not sure why that is .. I must be missing
>> something ..
> Doesn't clearcase play games with libc to create filesystem views
> organized to match the repository?  (I always found that kind of spooky:
> a revision control system which is also a rootkit...)

Nah, it's got a loadable kernel module that plugs into the vfs and looks
like a filesystem to the upper layers. Same idea as nullfs. But on the
lower end it does rpc's to a remote database 'version object base' aka
'vob' server, and has a cheap and cheerful local database cache aka a
'view' - also talked to through rpc over loopback I think. That's really
a thumbnail sketch and I'm probably mis-remembering a bunch of things.

Without the kernel module, it still does useful stuff, you can still use
something they call a snapshot view. In a snapshot view, the vob server
database gets blatted out onto a local filesystem and that effectively
becomes your cache - equivalent to cvs checkout'ing a code tree, and
works similarly.

Of course, on the kernel module side they support Linux, Sun(Sparc),
HP, AIX, and UW2 aka Novell Unix, or whatever it's called these days.

I've been told by grog and a few others that shimming the Linux kernel
module is pretty much a no-go because the Linux vfs api is quite different
from all others.

There might be a chance with the Uw2 module, but it's been quite a while
since I thought about trying it. ;)


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