2009/9/14 Leonidas . <leonidas137@xxxxxxxxx>: > > > On Mon, Sep 14, 2009 at 4:01 PM, Leonidas . <leonidas137@xxxxxxxxx> wrote: >> >> >> On Mon, Sep 14, 2009 at 3:32 PM, Leonidas . <leonidas137@xxxxxxxxx> wrote: >>> >>> >>> On Mon, Sep 14, 2009 at 3:28 PM, Leonidas . <leonidas137@xxxxxxxxx> >>> wrote: >>>> >>>> >>>> On Mon, Sep 14, 2009 at 2:46 PM, karunakar rao >>>> <karunakar.santhu@xxxxxxxxx> wrote: >>>>> >>>>> hi leo >>>>> maintain circular buffer in module, so that if user doesn't access for >>>>> days its going to be automatically discarded.I think printk also use same >>>>> kind of mechanism which dumps data into cirbuffer. >>>>> >>>>> thanks, >>>>> karuna. >>>>> >>>>> On Mon, Sep 14, 2009 at 2:41 PM, Leonidas . <leonidas137@xxxxxxxxx> >>>>> wrote: >>>>>> >>>>>> >>>>>> On Mon, Sep 14, 2009 at 2:30 PM, karunakar rao >>>>>> <karunakar.santhu@xxxxxxxxx> wrote: >>>>>>> >>>>>>> hi leo >>>>>>> you can maintain buffer in your module to log errors.When user tries >>>>>>> to access /proc you can print all those from your buffer. >>>>>>> >>>>>>> Thanks, >>>>>>> karuna. >>>>>>> >>>>>>> On Mon, Sep 14, 2009 at 1:22 PM, Leonidas . <leonidas137@xxxxxxxxx> >>>>>>> wrote: >>>>>>>> >>>>>>>> >>>>>>>> Hi List >>>>>>>> >>>>>>>> I have written a kernel module which implements a char device. An >>>>>>>> userspace app >>>>>>>> is supposed to get data from my module and then dump it into a file >>>>>>>> for further processing. >>>>>>>> >>>>>>>> The kind of data which kernel module is going to pass to userspace >>>>>>>> is going to be a 4K buffer, >>>>>>>> and the data traffic is not going to be really heavy, meaning may be >>>>>>>> a 4K buffer every 1 min or so. >>>>>>>> I am not very sure though, but certainly not heavy traffic the way >>>>>>>> they describe for network traffic etc. >>>>>>>> >>>>>>>> And this data needs to be logged to a file either from kernel or >>>>>>>> userspace and an userspace all will work >>>>>>>> on that data. This data needs to be logged as soon as it arrives >>>>>>>> meaning, I might not be able to write it to >>>>>>>> /proc since from module I can update /proc only when user actually >>>>>>>> accesses it. This data needs to be >>>>>>>> static in nature, meaning I get one error and I write it to a file >>>>>>>> somehow and user can see it anytime. >>>>>>>> >>>>>>>> I hope I have described the situation clearly. I have explored some >>>>>>>> mechanism like ioctls, mmaping the >>>>>>>> kernel buffer etc but all these would require the user module to >>>>>>>> poll or notified somehow by kernel that >>>>>>>> the data is available. I dont want the user module to poll. >>>>>>>> >>>>>>>> >>>>>>>> -Leo. >>>>>>>> >>>>>>> >>>>>> >>>>>> Pei Lin, >>>>>> >>>>>> I am not limiting my solution by using a law or what someone says. But >>>>>> I think it is very important to >>>>>> follow the spirit of environment/OS/arch you are working on and come >>>>>> up with the best possible solution. hi , i didn't receive these messages. (^-^) yeah,u can choose the way u wanna go,no matter a wide road or some private alleys. which one is convenient for different guys. >>>>>> As you correctly mention we can hack around and achieve the same >>>>>> functionality but I would rather do these >>>>>> kind of experiments for fun or to show my friends that the kernel can >>>>>> be hacked these ways, but certainly not >>>>>> in a system which is supposed to be a production system. I appreciate >>>>>> your thoughts and I am sure many times >>>>>> one stumbles upon real cool things which change course of nature and >>>>>> are reasons for radical changes in >>>>>> various subsystems. But I think this is not one of them, this has been >>>>>> discussed over and over again and there >>>>>> are standard interfaces defined. My questions is more about the design >>>>>> part not about how I can hack and get >>>>>> the stuff done. yeah,i agree. If it is a commercial software, it need a pretty and clean interface to support future updating and maintenance. >>>>>> >>>>>> Karuna, >>>>>> I had thought about this solution i.e. maintain a buffer in module and >>>>>> dump it whenever user wants, only >>>>>> issue is my module will keep consuming memory here. I msg buffers can >>>>>> be freed once logged but how about >>>>>> a case where user does not request for few days? The amount of memory >>>>>> my module is going to consume will be >>>>>> unacceptable. >>>>>> >>>>>> -Leo >>>>> >>>> >>>> Sorry I did not mention it earlier, I can not discard any error message >>>> logged, meaning these are error messages >>>> and might crash my system after a long time. I need to to be able to see >>>> all these messages till I restart my module. >>>> >>>> _Leo. >>> >>> >>> Basically, I am quite tight on memory and I would like to convery error >>> messages to user as soon as any >>> error condition is hit. So my module cant keep even 10 error msg which >>> will eat up 10 pages. >>> >>> _Leo >>> >>> >> >> Looks like some of the replys didn't get delivered to the list. Please >> refer the thread for someof the interactions. >> >> Isn't debugfs the right thing to use here? Anyone? Please enlighten. >> >> _Leo >> > > > After some analysis, I have decided to use netlink sockets for my use case. > Some queries regarding the same: > > 1. Are netlink sockets an overkill for not so heavy data transfer ? > 2. Do I have to recompile kernel etc for loading my module which usages > netlink sockets? > 3. Are they widely available everywhere? Meaning 2.4 and 2.6 kernles as > well? > 4. Any idea whether these are available on BSD kernel as well? I think they > are. > i think use sockets like using a big hammer knock to small nail...using signal to announce make more sense in my opinion. > > _Leo > > > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
