On Tuesday, April 11, 2006 4:59 pm, Ian Romanick wrote:
> I was a little mistaken about this. The BAR that causes the problem
> is not I/O. It *is* memory.
>
> 01:00.0 VGA compatible controller: Matrox Graphics, Inc. G400/G450
> (rev 03) (prog-if 00 [VGA])
> Subsystem: Matrox Graphics, Inc. Millennium G400 16Mb SGRAM
> Flags: bus master, medium devsel, latency 64, IRQ 11
> Memory at cc000000 (32-bit, prefetchable) [size=32M]
> Memory at cfefc000 (32-bit, non-prefetchable) [size=16K]
> Memory at cf000000 (32-bit, non-prefetchable) [size=8M]
> Expansion ROM at cfee0000 [disabled] [size=64K]
>
> When I open and mmap resource0 (the framebuffer) I get 0x2b9aa48ea000.
> When I open and mmap resource1 (the card's registers) I get
> 0x2b9aa68ea000. I can access the resource0 pointer all day long
> without problems. The firs access to the resource1 pointer results in
> a segfault.
Just tested on my x86-64 machine with this dumb little test program. It
seems to work ok, though I haven't tried writing data to the resource.
Jesse
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
int main(int argc, char *argv[])
{
size_t len;
int fd, i;
void *ptr;
uint32_t *val;
if (argc != 3) {
fprintf(stderr, "usage: %s <file> <mapsize>\n",
argv[0]);
return -1;
}
len = atoi(argv[2]);
fd = open(argv[1], O_RDONLY);
if (fd == -1) {
fprintf(stderr, "open failed: %s\n", strerror(errno));
return errno;
}
ptr = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
if (ptr == MAP_FAILED) {
fprintf(stderr, "mmap failed: %s\n", strerror(errno));
return errno;
}
val = ptr;
len = len / sizeof(uint32_t);
for (i = 0; i < len; i += 4) {
printf("%08x: 0x%08x 0x%08x 0x%08x 0x%08x\n", i * 4, val[i],
val[i+1], val[i+2], val[i+3]);
}
munmap(ptr, len); /* ignore any errors, we don't care */
close(fd);
return 0;
}
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