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SubjectRe: Alcatel SpeedTouch USB Modem
Thanks for that, Duncan. Lightweight and stable certainly sounds good; I
look forward to the project being ready.

Steve

On Fri, 21 Feb 2003, Duncan Sands wrote:

> On Friday 21 February 2003 03:01, Steve Parker wrote:
> > I see that the Alcatel kernel-level driver for the Alcatel SpeedTouch USB
> > Modem is now included in the 2.5 kernel.
>
> Hi Steve, that is so, and I am maintaining it.
>
> > This seems strange, since there seem to have been (in the past, at least)
> > a lot of (panic) problems reported with it, and the speedtouch.sf.net (and
> > complimentary speedtouchconf.sf.net) are fully capable of running this
> > modem in userspace.
> > Have these problems been resolved? Is the kernel driver as stable as the
> > userspace one? Are there demonstrable perfomance benefits in the kernel
> > driver?
>
> These problems are being resolved. Most of them have already been resolved.
> The cvs version for 2.4, which you can find at
>
> http://www.linux-usb.org/SpeedTouch/
>
> is quite stable. In theory it can still crash (due to various micro races), but in
> practice it does not. In any case, these micro races will be fixed soon. The
> 2.5 version, which is essentially identical to 2.4 cvs, doesn't work very well
> in the current 2.5 kernel. I don't know why. I am working on it.
>
> I have nothing against the user space version, which I used for many moons.
> The kernel version is certainly much lighter weight - less CPU, less memory.
> Whether this matters for you depends on your machine/needs. My machine
> is slow, and I need all the CPU time I can get!
>
> > I've certainly been using my modem for well over a year with the userspace
> > driver (speedtouch.sf.net) with - as at 2.4.18 - an unpatched kernel, and
> > no troubles whatsoever. Is there any need for the Alcatel code in the
> > kernel when the n_hdlc and ppp configs already cater for this modem, once
> > the microcode is loaded?
>
> The main disadvantages of the kernel mode driver were:
> (1) unstable, and very unstable on SMP/preempt boxes
> (2) required running the closed source speedmgmt program
> (3) required compiling your own kernel
>
> The driver is in 2.5, and is heading for inclusion in 2.4, so I expect that in the
> future most distributions will ship with the speedtch module compiled. Thus
> (3) is going away.
>
> The cvs version of the user space driver contains a patch for modem_run
> which enables it to be used with the kernel driver in place of speedmgmt
> (use the -k flag). Thus (2) has already gone away.
>
> As I mentioned, (1) is (almost) dealt with.
>
> > What is the status of this driver WRT the Alcatel microcode? Last I heard,
> > the Alcatel microcode was required by both the Alcatel kernel-level and
> > the speedtouch.sf.net drivers.
>
> That is correct, but you no longer need to upload it using speedmgmt.
> There are efforts underway to reverse engineer the microcode, with
> some success. The goal of writing our own microcode (ARM processor
> by the way) is still far, far away though.
>
> All the best,
>
> Duncan.
>

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