From owner-freebsd-hackers  Thu Dec  9  0:38: 3 1999
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Date: Thu, 9 Dec 1999 00:35:17 -0800
From: Jason Evans <jasone@canonware.com>
To: freebsd-hackers@freebsd.org
Subject: Possible libc changes to support LinuxThreads
Message-ID: <19991209003517.E73529@sturm.canonware.com>
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I've got a port of the most recent LinuxThreads (glibc-linuxthreads-2.1.2)
running, but ran into a couple of minor problems integrating with our libc.
LinuxThreads redefines a number of functions in order to make them either
support thread cancellation or work correctly.

The following functions need an alternative name, just as, for example,
write() is actually _write():

lseek()
pause()
system()
tcdrain()
wait()
waitpid()
recv()
send()

This would allow implementing cancellation points for these functions.  All
in all, I won't lose much sleep over this, but if it's easy to do and
doesn't violate some rule of symbol naming, it would be nice.

The other issue has to do with longjmp() and siglongjmp(), and is of a
similar nature, except that _longjmp() already exists as a separate
interface.  So, at least in the case of longjmp(), it needs to have a
different alias, perhaps __longjmp().  Below is a *very* simplistic patch
to libc that works, but it may make some people's skin crawl.  Feedback is
welcome.  If there is no correct way to create aliases to function entry
points, then we can do without them, but it will mean that the *jmp()
functions cannot be used in conjunction with thread cleanup handlers when
using LinuxThreads.

Jason

Index: i386/gen/setjmp.S
===================================================================
RCS file: /home/ncvs/src/lib/libc/i386/gen/setjmp.S,v
retrieving revision 1.11
diff -u -r1.11 setjmp.S
--- setjmp.S	1999/10/10 08:38:33	1.11
+++ setjmp.S	1999/12/09 02:07:45
@@ -54,6 +54,7 @@
 #include "DEFS.h"
 #include "SYS.h"
 
+ENTRY(__setjmp)
 ENTRY(setjmp)
 	movl	4(%esp),%ecx
 	PIC_PROLOGUE
@@ -80,6 +81,7 @@
 	xorl	%eax,%eax
 	ret
 
+ENTRY(__longjmp)
 ENTRY(longjmp)
 	movl	4(%esp),%edx
 	PIC_PROLOGUE
Index: i386/gen/sigsetjmp.S
===================================================================
RCS file: /home/ncvs/src/lib/libc/i386/gen/sigsetjmp.S,v
retrieving revision 1.13
diff -u -r1.13 sigsetjmp.S
--- sigsetjmp.S	1999/09/29 15:18:35	1.13
+++ sigsetjmp.S	1999/12/09 02:07:45
@@ -59,6 +59,7 @@
  *	use sigreturn() if sigreturn() works.
  */
 
+ENTRY(__sigsetjmp)
 ENTRY(sigsetjmp)
 	movl	8(%esp),%eax
 	movl	4(%esp),%ecx
@@ -89,6 +90,7 @@
 	xorl	%eax,%eax
 	ret
 
+ENTRY(__siglongjmp)
 ENTRY(siglongjmp)
 	movl	4(%esp),%edx
 	cmpl	$0,44(%edx)


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