why u must use a law to limit your solution? And u can hack kernel and dig the hole and do what u want...... Lin 2009/9/14 Leonidas . <leonidas137@xxxxxxxxx>: > > > On Mon, Sep 14, 2009 at 2:19 PM, Leonidas . <leonidas137@xxxxxxxxx> wrote: >> >> >> On Mon, Sep 14, 2009 at 1:57 PM, Pei Lin <telent997@xxxxxxxxx> wrote: >>> >>> SO u can use the first method,write files from the kernel space..... >>> See the hyperlink i give. >>> >>> Lin >>> >>> 2009/9/14 Leonidas . <leonidas137@xxxxxxxxx>: >>> > >>> > >>> > 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. >>> >> >>> > >>> > When we do a printk it writes to kernel log buffer, correct? This is >>> > real in >>> > time operation i.e. as soon as we do a >>> > printk the messages get logged. Now this log file can be accesses from >>> > /var/log/messages right? How is this done? >>> > >>> > I want to so something similar, so I can log my messages to a seprate >>> > file >>> > which is going to stay around so user can >>> > see at across reboots as well. >>> > >>> > >>> > >>> > -Leo. >>> > >>> > >> >> >> No, Greg KH mentions that is should not be done! >> And I have been reading that 'It is a bad..bad thing to access files from >> kernel space' >> since I started doing Linux stuff. >> >> _Leo. > > > I am aware of other legitimate mechanisms as I have described on my origianl > post. > It is just that I have certain constraints under which I cant use many of > the methods > since I dont want to user space entity to do polling or get signal from > kernel. > > -Leo. > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
