> Duncan wrote: > Anyway, I was hacking away on it the other day when a > luminous thought struck me: "Why not use the user space > driver instead?"
Indeed. I think the user-space option offers a lot for people that just want to get it working with minimal fuss. I had tried to get the kernel- mode driver working with little success, and I consider myself pretty adept at the whole kernel hacking thing. > The main advantage of the kernel space driver is that it > has very low overhead: it gets data from (and sends data > to) the modem extremely fast, with a minimum of CPU > use. Should make a difference to latency (has anyone actually measured the difference?). I don't care about CPU use as my ADSL is on a dedicated box (it uses <1% of a Cyrix MII-400). Other users may notice this more though. > [The main disadvantages of the kernel space driver (for me) > are: (1) some closed source code is run (management daemon), The closed source module does the same as modem_run (although it probably understands the status messages). Namely: a) Upload microcode to modem (this will never be free, it has to come from somewhere until someone brave re-writes the ARM microcode which would be no mean feat). b) Send activation commands to sync up (if we knew the exact format we could do things like alter bandwidth settings and latency settings but I suspect most ISP's have the CO manage the ADSL negotiation) c) Terminate the regular status messages to keep the modem happy I think it has been suggested you could use modem_run with the kernel mode drivers. After all modem_run doesn't care about the ATM USB connection (which I assume is silently munched by the ATM "device" in the kernel mode implementation). > (2) it requires patching pppd for PPP over ATM.] Until ATM (and the kernel mode driver) gets into the mainstream kernel this will be an issue for the majority of users. Also I can't seem to find who maintains ppp these days so it may be a while before the ATM patches go into the mainstream pppd. > My question is: is the extra overhead of the user space driver > worth caring about? IMNSHO not really, but I wait for someone to show me some comparative benchmarks. I can play Counter-Strike on my setup and still blow away those poncy 56k users :-) > In other words: should I stop hacking the kernel module? Its a personnel choice, certainly a USB kernel hacker will be a useful addition to the coding community (I must ask you about device resets at some point) but in the end you should do what makes you happy. Alex. Liste de diffusion modem ALCATEL SpeedTouch USB Pour se désinscrire : mailto:[EMAIL PROTECTED]?subject=unsubscribe
