Re: Porting vfork()

Brandon S. Allbery KF8NH (allbery@kf8nh.apk.net)
Mon, 11 Jan 1999 06:54:49 -0500

In message <Pine.LNX.4.04.9901110451590.19839-100000@dahlin.fairplay.no>,
Torbj
orn Lindgren writes:
+-----
| > | The requirements are basically (paraphrased):
| > | * Don't modify any data other than a variable of type pid_t used to store
| > | the return value from vfork()
| > | * Don't return from the function in which vfork() was called.
| > | * Don't call any functions before successfully calling _exit(),or one of
| > | the exec family of functions.
| >
| > The restrictions are consistent with safety requirements when using a "true"
| > vfork(), so Solaris's implementation is valid. SUS is simply saying that
|
| According to the Solaris man-pages (5.5.1) it suspends the calling thread
| until the child either calls exec*() or exits.
+--->8

Yes, which requires the restrictions above else all hell breaks loose....

I think you still misunderstand the point of the spec: vfork() *can* be
fork(), but you have to follow the restrictions in case it's the hacky
ancient-VAX bug workaround Solaris and a few others use. I get the
impression that SUS disapproves of the hacky implementation, but still
considers it valid (presumably because it wouldn't do to exclude Sun from
SUS compliance).

-- 
brandon s. allbery	[os/2][linux][solaris][japh]	 allbery@kf8nh.apk.net
system administrator	     [WAY too many hats]	   allbery@ece.cmu.edu
carnegie mellon / electrical and computer engineering			 KF8NH
     We are Linux. Resistance is an indication that you missed the point.






-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/