vxWorks 6.8 mapping physical to virtual memory

问题:

This is my first question here :).

I been trying for while now to map physical memory to virtual memory in vxWorks 6.8 with no success, I'm trying to use "vmMap" function but somehow it keeps return with:

errno = 0x30065 S_taskLib_NAME_NOT_FOUND.

my code is:

int page_size=0;
PHYS_ADDR GPIO_BASE_VIRTUAL_ADDR = 0x40E00000;
VIRT_ADDR VIRTUAL_ADDR=0;

page_size =vmPageSizeGet();
if((VIRTUAL_ADDR = (VIRT_ADDR)memalign(page_size,page_size*2))==NULL)// allocate 2 pages 
{
    printf("error in memalign() errno = 0x%x\n",errnoGet());
}

if(vmMap(NULL,VIRTUAL_ADDR,GPIO_BASE_VIRTUAL_ADDR,(page_size*2))== ERROR )
{
    printf("Error mapping memory errno = 0x%x%\n",errnoGet());
}

Any help will be very appreciate, thanks,

Moshe.

回答1:

I see you already solved this long ago, but thought I'd leave some bread crumbs for whoever else might stumble this way in the dim & distant future..

Unless you're doing RTPs there's a good chance your MMU isn't even translating addresses. I.e., if something appears at say, 0x7fc00400 in the physical address space, you could simply cast that value to a pointer and use it.

*((short *) 0x7fc00400) = foo; // write 16 bits!

And Yes, these days it is almost sacrilege to suggest (ab)using pointers this way, but I would point out that if you're doing vxworks kernel space code, you're practically on the bare metal anyway, so why not?