Re: [rtl] Re: your mail

[Michael Barabanov <baraban@fsmlabs.com>]

Hi Tomek,

mmap and other posix file functions are supported in rtl_posixio.o,
so mmap is available for RT-threads. mmap on /dev/mem does
ioremap internally. This is more of a proof of concept
right now, but it does work. See examples/mmap.

Michael.

Tomasz Motylewski (motyl@stan.chemie.unibas.ch) wrote:
> On Fri, 21 Apr 2000, Zhixu Liu wrote:
> 
> > I have a question about the share memory use mmap. (in rtlinux-2.2)
> > I use the example in mmap, but what i want to know is is there is a 
> 
> mmap is for user space. Use ioremap in the kernel.
> 
> > limit of the size of share memory, for when i try to map a region
> > about 1000 int, in the kernel module the computer always dead.
> > 
> > Following is the program i use.
> > 
> > ===================================
> > #include <rtl.h>
> > #include <unistd.h>
> > #include <fcntl.h>
> > #include <sys/mman.h>
> 
> Did you compile it with -D__KERNEL__ etc. ? You should not include things
> like unistd.h or fcntl.h or sys/mman.h in kernel space. They are unusable
> there anyway.
> 
> > 	int fd = open("/dev/mem", O_RDWR);
> I do not think it is supported in the kernel.
> 
> > 	start = (int *)mmap(0,length*sizeof(int),PROT_READ|PROT_WRITE,
> > 			MAP_SHARED,fd,BASE_ADDRESS);
> 
> Just use ioremap instead.
> 
> --
> Tomek