Three ways I know of are: 1) proc interface 2) software device driver 3) netlink sockets. I guess most addressed software device driver, using ioctl. proc interface is easier to write. oh ya, don't forget sysctl too. Eugene <quote sender="Prokopenko, Konstantyn"> > Hi. > > If you have small amount of data and no hard real-time performance needed > you can use slow copy_to_user/copy_from_user macros. > The fastest way to share data between user space and several devices is to > map physical memory > into kernel and user's virtual spaces. This is a very interesting technique > allows you to AVOID at least one data copy from user to kernel and back. If > you are moving large amount of data plus performing DMA to/from your > device(s) - this is the way. > Now, there are several options to do that. > 1. Allocate contiguous physical memory using bootmem_allocator (requires > your driver to be built-in) > 2. Allocate contiguous physical memory using mem=XXX parameter to get > unmanageable chunk of memory. > > 'ioremap' the physical memory into kernel's space and implement 'mmap' to > map the memory chunk into user virtual space and bingo! - you can access the > chunk of memory from user and kernel space without extra or no copies at > all. > If you have DMA transactions - the memory is already contiguous. Using > ioctls, spin-locks or other methods you can synchronize access to this > shared memory from user applications and kernel methodes and isr. > > Regards, > Konstantyn. > > > -----Original Message----- > From: Danilo Reinhardt [mailto:Danilo.Reinhardt@de.bosch.com] > Sent: Monday, April 05, 2004 5:38 AM > To: kernelnewbies@nl.linux.org > Subject: Exchange Date Userspace<->Kernel > > > Hi, > > I want to develop a driver that exchanges/modifies data between 2 > devices. Now I try to find out whats the best way to do this. > > I think there are 2 ways to do it, the first by doing all work inside > the driver, and the secondy by passing the data from the driver to an > userspace programm which handles and forwards the data to the second > device. > > Whats the fastest way to exchange data between the kernel and a > userspace process and how fast is it? > > And on the other side, whats the best way to exchange data inside the > kernel between 2 devices (which are handled by the same driver!). > > Thanks for all replies! > > Bye Dan > > > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > > -- Eugene TEO - <eugeneteo%null!cc!uic!edu> <http://www.anomalistic.org/> 1024D/14A0DDE5 print D851 4574 E357 469C D308 A01E 7321 A38A 14A0 DDE5 main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); } -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
