Make futexes work under NOMMU conditions.
This can be tested by running this in one shell:
#define SYSERROR(X, Y) \
do { if ((long)(X) == -1L) { perror(Y); exit(1); }} while(0)
int main()
{
int shmid, tmp, *f, n;
shmid = shmget(23, 4, IPC_CREAT|0666);
SYSERROR(shmid, "shmget");
f = shmat(shmid, NULL, 0);
SYSERROR(f, "shmat");
n = *f;
printf("WAIT: %p{%x}\n", f, n);
tmp = futex(f, FUTEX_WAIT, n, NULL, NULL, 0);
SYSERROR(tmp, "futex");
printf("WAITED: %d\n", tmp);
tmp = shmdt(f);
SYSERROR(tmp, "shmdt");
exit(0);
}
And then this in the other shell:
#define SYSERROR(X, Y) \
do { if ((long)(X) == -1L) { perror(Y); exit(1); }} while(0)
int main()
{
int shmid, tmp, *f;
shmid = shmget(23, 4, IPC_CREAT|0666);
SYSERROR(shmid, "shmget");
f = shmat(shmid, NULL, 0);
SYSERROR(f, "shmat");
(*f)++;
printf("WAKE: %p{%x}\n", f, *f);
tmp = futex(f, FUTEX_WAKE, 1, NULL, NULL, 0);
SYSERROR(tmp, "futex");
printf("WOKE: %d\n", tmp);
tmp = shmdt(f);
SYSERROR(tmp, "shmdt");
exit(0);
}
The first program will set up a SYSV IPC SHM segment and wait on a futex in it
for the number at the start to change. The program will increment that number
and wake the first program up. This leads to output of the form:
SHELL 1 SHELL 2
======================= =======================
# /dowait
WAIT: 0xc32ac000{0}
# /dowake
WAKE: 0xc32ac000{1}
WAITED: 0 WOKE: 1
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add documentation about using shared memory in NOMMU mode.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make mremap() partially work for NOMMU kernels. It may resize a VMA provided
that it doesn't exceed the size of the slab object in which the storage is
allocated that the VMA refers to. Shareable VMAs may not be resized.
Moving VMAs (as permitted by MREMAP_MAYMOVE) is not currently supported.
This patch also makes use of the fact that the VMA list is now ordered to cut
it short when possible.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Implement /proc/pid/maps for NOMMU by reading the vm_area_list attached to
current->mm->context.vmlist.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
David Howells
Linus Torvalds