[9fans] problem with rminnich's 9vx

[rminnich@gmail.com (ron minnich)]

This one is extremely weird.

On Tue, Mar 29, 2011 at 2:00 AM, Mathieu Lonjaret
<mathieu.lonjaret at gmail.com> wrote:
> Hi all,
>
> this is probably trivial; this is what I get when trying to start 9vx:
>
> Warning! factotum can't protect itself from debugging: '#p/5' file does not exist
> init: warning: can't open #p/2/ctl: '#p/2' file does not exist

If #p does not work, well! things are seriously wrong. Do you ever get
an rc prompt?

Oh, I see; it's the ubuntu + sprintf problem. I should have taken
Christoph's patch, sorry about that; my fault.

As to your other questions. There's no real reason to build 9vx as a
64-bit binary, and it causes a lot of headaches, so I stick with a
32-bit version nowadays; also, I build all my binaries using my
sysfromiso repo as a starting point. In fact I build all my arm
kernels on 9vx using sysfromiso and use 9vx as the server for the root
file system for the ARMs. In spite of everything I much prefer hg to
replica.

We need a better way to keep 9vx going than just "Ron's version" or
"Joe's version" or whatever. Certainly patches should not just be
directed to me. I don't see the harm in bringing the discussions to
this list.

Here's the patch in question.

 sprint(char *buf, char *fmt, ...)
 {
 	int n;
-	uint len;
 	va_list args;

-	len = 1<<30;  /* big number, but sprint is deprecated anyway */
-	/*
-	 * on PowerPC, the stack is near the top of memory, so
-	 * we must be sure not to overflow a 32-bit pointer.
-	 */
-	if(buf+len < buf)
-		len = -(uintptr)buf-1;
-
 	va_start(args, fmt);
-	n = vsnprint(buf, len, fmt, args);
+	n = vsnprint(buf, 65536, fmt, args);
 	va_end(args);
 	return n;
 }

Note the len = 1 << 30; why was that ever done? I never figured that
out so was never sure about the implications of this patch. Anybody
know?

thanks

ron