Hello cinap,
My experiment here.
void
main(int argc, char *argv[])
{ char *ap;
char buf[1];
ARGBEGIN{
default: usage();
}ARGEND
ap = segattach(0,"share",0,1024);
print("%p\n",ap); // ffffffff error
/* compare */
ap = sbrk(0);
print("sbrk %p\n",ap); // 6cb0
ap += 2*1024*1024;
print("%p\n",ap); // 206cb0
ap = segattach(0, "shared", ap, 1024);
print("%p\n",ap); // 206000
read(0,buf,1);
}
we can find the allocated share memory:
term% cat /proc/612768/segment
Stack defff000 dffff000 1
Text R 1000 6000 1
Data 6000 7000 1
Bss 7000 7000 1
Shared 206000 207000 1
term%
note that 0x206cb0 + 0x400 > 0x20700.
if we believe that we have a memory
of range [mp,mp+1024) by executing
mp = share(1024)
then we will fail.
Kenji Arisawa
2014/09/14 12:17、[email protected] のメール：
> it should round va down and va+len up as neccesary
> to make them page aligned. but the initial passed
> range should be covered by the created segment
> in any case.
