On Sat, May 04, 2002 at 11:08:43PM -0500, Ben Winslow wrote:
> This turned out to be a problem with CONFIG_FPE_FASTFPE
> (CONFIG_FPE_NWFPE works fine.) Thanks to everyone who provided insight
> into the problem.
On Mon, Jun 17, 2002 at 11:32:21AM -0700, Tony Lindgren wrote:
> * mallum <[EMAIL PROTECTED]> [020614 07:13]:
> > I too have this exact same problem on a CATS machine running debian
> > unstable ( kernel 2.4.18-rmk6 ).
> >
> > Is the only fix to link to debug-perl ?
> >
> > -- Matthew
>
> Hi,
>
> Well, I finally got around to verifying that this is caused by the Fast
> Floating Point Emulator. So the real solution is to use the Netwinder
> Floating Point Emulator. Symlinking perl to debug-perl seems to be a
> work around with the Fast Floating Point Emulator.
>
> In any case, it's weird how the FastFPE works with debug-perl and not
> with perl...
>
> Tony
I wasn't aware of anyone getting this down to a test case.
The problem seems to be saving a floating point register containing 0 to
memory, and then reloading it. The same binaries give:
[EMAIL PROTECTED] [test]$ ./is_zero
1
[EMAIL PROTECTED] [test]$ ./is_one
1
[EMAIL PROTECTED] [test]$ dmesg | grep -i Floating
NetWinder Floating Point Emulator V0.95 (c) 1998-1999 Rebel.com
[EMAIL PROTECTED] [test]$ ./is_zero
0
[EMAIL PROTECTED] [test]$ ./is_one
1
[EMAIL PROTECTED] [test]$ dmesg | grep -i Floating
Fast Floating Point Emulator V0.9 (c) Peter Teichmann.
If I take the lfmfd out from this then it all works as expected on FastFPE
mvfd f1, #0
sfmfd f1, 1, [sp]!
lfmfd f1, 1, [sp]!
mvfd f0, #0
cmf f0, f1
[EMAIL PROTECTED] [test]$ ./is_zero_noload
1
Attached are source for is_zero and is_one
Nicholas Clark
--
Even better than the real thing: http://nms-cgi.sourceforge.net/
@ Generated by gcc 2.95.4 20010319 (Debian prerelease) for ARM/elf
.file "temp.c"
gcc2_compiled.:
.section .rodata
.align 2
.LC0:
.ascii "%d\012\000"
.text
.align 2
.global main
.type main,function
main:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 1, current_function_anonymous_args = 0
mov ip, sp
stmfd sp!, {r4, fp, ip, lr, pc}
sub fp, ip, #4
mvfd f1, #0
sfmfd f1, 1, [sp]!
lfmfd f1, 1, [sp]!
mvfd f0, #0
cmf f0, f1
movne r1, #0
moveq r1, #1
ldr r0, .L149
bl printf
.L150:
.align 2
.L149:
.word .LC0
.L148:
mov r0, #0
ldmea fp, {r4, fp, sp, pc}
.Lfe2:
.size Perl_pp_eq,.Lfe2-Perl_pp_eq
.ident "GCC: (GNU) 2.95.4 20010319 (Debian prerelease)"
@ Generated by gcc 2.95.4 20010319 (Debian prerelease) for ARM/elf
.file "temp.c"
gcc2_compiled.:
.section .rodata
.align 2
.LC0:
.ascii "%d\012\000"
.text
.align 2
.global main
.type main,function
main:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 1, current_function_anonymous_args = 0
mov ip, sp
stmfd sp!, {r4, fp, ip, lr, pc}
sub fp, ip, #4
mvfd f1, #1
sfmfd f1, 1, [sp]!
lfmfd f1, 1, [sp]!
mvfd f0, #1
cmf f0, f1
movne r1, #0
moveq r1, #1
ldr r0, .L149
bl printf
.L150:
.align 2
.L149:
.word .LC0
.L148:
mov r0, #0
ldmea fp, {r4, fp, sp, pc}
.Lfe2:
.size Perl_pp_eq,.Lfe2-Perl_pp_eq
.ident "GCC: (GNU) 2.95.4 20010319 (Debian prerelease)"
