[gentoo-user] slotted package - how to switch

[Helmut Jarausch]

Sorry if this is FAQ but I couldn't find the answer.
E.g. I have to versions of dev-libs/libusb installed, one in slot 0 and
the other one in slot 1.
For testing purposes I'd like to make the slot-0 version 'effective'.
How can I do that (other than unmerging the slot-1 version)
ASAIK, eselect cannot do this.

Many thanks for a hint,
Helmut.

--
Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany

[Alan McKinnon]

On Thursday 12 November 2009 13:05:29 Helmut Jarausch wrote:
> Sorry if this is FAQ but I couldn't find the answer.
> E.g. I have to versions of dev-libs/libusb installed, one in slot 0 and
> the other one in slot 1.
> For testing purposes I'd like to make the slot-0 version 'effective'.
> How can I do that (other than unmerging the slot-1 version)
> ASAIK, eselect cannot do this.

Why do you want to do that? The package contains only libs, and apps that link
to it already know which on they want.

I suppose you could tinker with LDPATH but I think there's a basic
misunderstanding of what the package is

--
alan dot mckinnon at gmail dot com

[Helmut Jarausch]

The reason is the following bug.
To use an old printer (no USB connector) I've purchased
a USB-to-parallel adapater (since some software like VirtualBox
cannot handle the parallel port).

[my bug report 291596] :

When I use 'add printer' from the cups web interface this "printer" isn't
shown and I get the following entry in /var/log/messages:
Nov 2 16:19:41 numa-be kernel: usb[9750]: segfault at 7fff14c30000 ip
00007f8d3a50dc0b sp 00007fff14c2ced8 error 4 in
libc-2.10.1.so[7f8d3a490000+14d000]

I have started cupsd in foreground but it doesn't show any errors.
Where does this error come from?

-----

Robin Johnson replied
Did this work on:
- a previous kernel?
- the libusb-0* series?
- ever (what changed since then)?

Therefore I'd like to test with the older libusb.

Many thanks for your help,

[William Kenworthy]

Just a thought as I have not been following the thread - why not use a
network printer? If its gentoo in a virtualbox on a windows machine you
can share the windows printer and use cups on the linux side to redirect
to it via samba. No need to worry about parallel ports or physical
printer connections in the vm, and the original host can continue to use
the printer on the parallel port.

http://www.gentoo.org/doc/en/printing-howto.xml

Apologies if its already been mentioned.
BillK

[Helmut Jarausch]

There are 2 reasons.

First, for my PC at home, I don't have a local network and my old
printer cannot be connected to a network.

Here, at our institute, we have some small (old) printers within a small
office (in addition to copiers connected by TCP/IP)

[Alex Schuster]

Helmut Jarausch writes:

> >> The reason is the following bug.
> >> To use an old printer (no USB connector) I've purchased
> >> a USB-to-parallel adapater (since some software like VirtualBox
> >> cannot handle the parallel port).

[...]

> First, for my PC at home, I don't have a local network and my old
> printer cannot be connected to a network.
>
> Here, at our institute, we have some small (old) printers within a
> small office (in addition to copiers connected by TCP/IP)

There are also cheap ethernet-to-parallel adapters that you could use
instead of the usb-to-parallel one. Or add an ethernet-to-usb adapter to
the chain :)

Wonko

[Alan McKinnon]

In that case I would quickpkg libusb, downgrade and test. Then reply to Robin,
and put the recent libusb back. At this stage you don't want to make a
permanent change (yet), just test a theory