Messages in this thread | | | Date | Wed, 06 Aug 2003 16:24:22 -0600 | From | Scott Jacobsen <> | Subject | mmap, PCI, segmentation fault, Dell Dimension 4550 |
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Hi. Sorry for the intrusion but I've searched the archives and can't seem to find the answer for my problem.
After using mmap() map a peripheral card's PCI base address registers to user space on my Dell Dimension 4550 (Dell BIOS), I cause a segmentation fault by accessing the mapped memory.
My OS is Redhat 9 and the underlying kernel is 2.4.20-8. The code works fine on a generic computer (Award BIOS) running exactly the same kernel.
My driver for the card also maps the PCI base address registers in kernel space for the driver's usage, but like I mentioned, the code works fine on the other computer.
Here's my code and command line output (please pardon my non-gdb testing procedure):
////////////////////// code /////////////////////////
int Software_Radio::get_bars() { printf("get_bars\n"); // TEST LINE uchar config_data[256]; off_t physical_bars[5];
if(ioctl(filep, CONFIG_READ, config_data) == -1) perror("\nSoftware_Radio::get_bars() ioctl() CONFIG_READ failed");
physical_bars[0]=((off_t)config_data[PCI_BASE_ADDRESS_0] | ((off_t)config_data[PCI_BASE_ADDRESS_0 + 1] << 8) | ((off_t)config_data[PCI_BASE_ADDRESS_0 + 2] << 16) | ((off_t)config_data[PCI_BASE_ADDRESS_0 + 3] << 24) ); physical_bars[1]=((off_t)config_data[PCI_BASE_ADDRESS_1] | ((off_t)config_data[PCI_BASE_ADDRESS_1 + 1] << 8) | ((off_t)config_data[PCI_BASE_ADDRESS_1 + 2] << 16) | ((off_t)config_data[PCI_BASE_ADDRESS_1 + 3] << 24) ); physical_bars[2]=((off_t)config_data[PCI_BASE_ADDRESS_2] | ((off_t)config_data[PCI_BASE_ADDRESS_2 + 1] << 8) | ((off_t)config_data[PCI_BASE_ADDRESS_2 + 2] << 16) | ((off_t)config_data[PCI_BASE_ADDRESS_2 + 3] << 24) ); physical_bars[3]=((off_t)config_data[PCI_BASE_ADDRESS_3] | ((off_t)config_data[PCI_BASE_ADDRESS_3 + 1] << 8) | ((off_t)config_data[PCI_BASE_ADDRESS_3 + 2] << 16) | ((off_t)config_data[PCI_BASE_ADDRESS_3 + 3] << 24) ); physical_bars[4]=((off_t)config_data[PCI_BASE_ADDRESS_4] | ((off_t)config_data[PCI_BASE_ADDRESS_4 + 1] << 8) | ((off_t)config_data[PCI_BASE_ADDRESS_4 + 2] << 16) | ((off_t)config_data[PCI_BASE_ADDRESS_4 + 3] << 24) );
int fd; if((fd=open("/dev/mem",O_RDWR)) < 0) { perror("opening /dev/mem"); return -1; } unsigned long * remapped_bars[5]; void * temp; for (int i = 0; i < 5; i++) { if((temp = mmap(0,bar_sizes[i],PROT_WRITE | PROT_READ, MAP_SHARED | MAP_FILE, fd, physical_bars[i])) < 0) { printf("MMAP failed. Reason: %s\n",strerror(errno)); return -1; } remapped_bars[i] = (unsigned long *)temp; } bar0 = remapped_bars[0]; printf("bar0 = 0x%x\n",&bar0); // TEST LINE printf("bar0[15] = 0x%x\n",bar0[0]); // THIS LINE, OR ANY bar0[0] CAUSES A SEGMENTATION FAULT bar1 = remapped_bars[1]; bar2 = remapped_bars[2]; bar3 = remapped_bars[3]; bar4 = remapped_bars[4]; close(fd); }
/////////////////// command line //////////////////
[root@jacobsen swr]# ./test main:line 1 opening device /dev/sidrv0 get_bars bar0 = 0xbfffe0b0 Segmentation fault [root@jacobsen swr]#
//////////////////////////////////////////////////
Any suggestions?
Thanks,
Scott Jacobsen MSc(Eng) Student University of Calgary
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