Hi Steven, > I have a little question just as the title said? > In Ofono how to connect PPP to Linux socket, when we receive packet > from network, how the packet go through the kernel to application？ > > modem -->PPP-->? --> linux kernel(network part)--> socket --> > application? it is more like this: modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> application. With the TTY being in kernel, the PPP being in userspace, and TUN/TAP etc. begin in the kernel again. A future enhancement is to use the kernel PPP layer, but we haven't gotten there yet.

Regards Marcel _______________________________________________ ofono mailing list ofono(a)ofono.org http://lists.ofono.org/listinfo/ofono

Hi Marcel, Marcel Holtmann wrote: > Hi Steven, > >> I have a little question just as the title said? >> In Ofono how to connect PPP to Linux socket, when we receive packet >> from network, how the packet go through the kernel to application？ >> >> modem -->PPP-->? --> linux kernel(network part)--> socket --> >> application? > it is more like this: > > modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> > application. > > With the TTY being in kernel, the PPP being in userspace, and TUN/TAP > etc. begin in the kernel again. > > A future enhancement is to use the kernel PPP layer, but we haven't > gotten there yet. I am interested to know how could we use kernel PPP layer instead of gatppp. Shall we add this item into our TODO?

Hi Steven, Steven wrote: > Hi Zhang > Zhang, Zhenhua wrote: >> Hi Marcel, >> >> Marcel Holtmann wrote: >>> Hi Steven, >>> >>>> I have a little question just as the title said? >>>> In Ofono how to connect PPP to Linux socket, when we receive packet >>>> from network, how the packet go through the kernel to application？ >>>> >>>> modem -->PPP-->? --> linux kernel(network part)--> socket --> >>>> application? >>> it is more like this: >>> >>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> >>> application. >>> >>> With the TTY being in kernel, the PPP being in userspace, and >>> TUN/TAP etc. begin in the kernel again. >>> >>> A future enhancement is to use the kernel PPP layer, but we haven't >>> gotten there yet. >> I am interested to know how could we use kernel PPP layer instead of >> gatppp. Shall we add this item into our TODO? >> > Maybe you can reference to RILD in Android, it used kernel PPP. Thanks. Will take a look then.

>>>>>> I have a little question just as the title said? >>>>>> In Ofono how to connect PPP to Linux socket, when we receive >>>>>> packet from network, how the packet go through the kernel to >>>>>> application？ >>>>>> >>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket --> >>>>>> application? >>>>> it is more like this: >>>>> >>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> >>>>> application. >>>>> >>>>> With the TTY being in kernel, the PPP being in userspace, and >>>>> TUN/TAP etc. begin in the kernel again. >>>>> >>>>> A future enhancement is to use the kernel PPP layer, but we >>>>> haven't gotten there yet. >>>> I am interested to know how could we use kernel PPP layer instead >>>> of gatppp. Shall we add this item into our TODO? >>>> >>> Maybe you can reference to RILD in Android, it used kernel PPP. >> >> Thanks. Will take a look then. > > This information is a good start point. > http://www.devdiv.net/viewthread-26543 > > But only for Chinese people:( Thanks. I have read this before. ;-). The original article is from maxleng's blog: http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer.

>>>>>>>> I have a little question just as the title said? >>>>>>>> In Ofono how to connect PPP to Linux socket, when we receive >>>>>>>> packet from network, how the packet go through the kernel to >>>>>>>> application？ >>>>>>>> >>>>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket --> >>>>>>>> application? >>>>>>> it is more like this: >>>>>>> >>>>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> >>>>>>> application. >>>>>>> >>>>>>> With the TTY being in kernel, the PPP being in userspace, and >>>>>>> TUN/TAP etc. begin in the kernel again. >>>>>>> >>>>>>> A future enhancement is to use the kernel PPP layer, but we >>>>>>> haven't gotten there yet. >>>>>> I am interested to know how could we use kernel PPP layer instead >>>>>> of gatppp. Shall we add this item into our TODO? >>>>>> >>>>> Maybe you can reference to RILD in Android, it used kernel PPP. >>>> Thanks. Will take a look then. >>> This information is a good start point. >>> http://www.devdiv.net/viewthread-26543 >>> >>> But only for Chinese people:( >> Thanks. I have read this before. ;-). The original article is from maxleng's blog: >> >> http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx >> >> However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer. > > could be that Andoid uses the kernel PPP and also uses pppd for it. We > are not using pppd on purpose since it is the wrong piece for an > embedded phone solution. We are not using the kernel PPP part, because > we haven't gotten around that yet. It also only works when having real > TTY devices. I don't think using pppd is a wrong piece for embedded phone, if we using pppd, we can ease the ppp part of ofono and also support full ppp functionalities, such as auth method(plain text, pap, chap, eap and so on)

If your multiplexer runs in userspace then you also have > the problem that you don't have a real TTY. And using a PTS, then you > can just run PPP also in userspace. A little question, if we runs multiplexer in kernel space, can we using kernel ppp part?

> for a mobile telephony stack, pppd is wrong. Once you understand how 3G > missuses PPP for IP and PDP context setup, you see what I mean ;) For mobile telephony, PPP as a _protocol_ is wrong - sure. That being stated, I don't see how pppd as a _software_ is better or worse than any other PPP implementation. Considering the high bandwidth involved in high HSPA categories, and soon LTE networks, going through user space seems like a bad idea. That's why Phonet GPRS has its own kernel network device driver, even though Phonet can also interact with a TUN device. As such, the PPP-only modems are hopeless. Then why bother rewriting a custom PPP implementation that will be suboptimal in any case? oFono PPP is just as non-performant as pppd in case the user-space AT MUX is used. And it seems worse in case the kernel AT MUX or a raw TTY is used (pppd has kernel path then).