On Mon, Nov 13, 2006 at 04:30:26PM +0100, Mile Davidovic wrote: > ptr = (unsigned char*)mmap(0,lineSize,PROT_READ|PROT_WRITE,MAP_SHARED,fd0,0); > ... > for (i = 0; i < 12; i++) > *ptr++ = 0xaa; > > this loop will not write all bytes correctly (every 4 bytes will have 0xaa as > value), here is dump from Lauterbach debugger: > ___address__|_0________4________8________C________0123456789ABCDEF > D:83660000|>FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF ................ > D:83660010| 000000AA 000000AA 000000AA 0000AA02 ................ Is 83660000 a proper physical address or a virtual address? A common mistake is mapping a KSEG _virtual_ address to a userspace _virtual_ address. Obviously mapping anything virtual to something else virtual doesn't work ... > and if I use bigger loop > for (i = 0; i < 20; i++) > *ptr++ = 0xaa; > My linux will be crashed on 13 write. So, this is reason why I thought that > byte access is not allowed on mmaped uncached memory. Let me guess, you filled up some write queue which now is waiting for an acknowledge which never arrives. > Is it possible that problem with byte access is related with device mmap > function? That is fairly simple code. Ralf
