2005-09-13 08:58:56

by Chuck Ebbert

Subject: [patch 2.6.13] i386: Ignore masked FPU exceptions

I think ignoring masked FPU exceptions on i386 is the right thing to do.
Although there is no documentation available for Cyrix MII, I did find
erratum F-7 for Winchip C6, "FPU instruction may result in spurious
exception under certain conditions" which seems to indicate that this can
happen.

Ondrej, this patch on top of 2.6.13 should fix your Cyrix problems.
Can you confirm? There was another bug which was already fixed,
so this should be all that's needed now.

Signed-off-by: Chuck Ebbert <[email protected]>

arch/i386/kernel/traps.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

--- 2.6.13a.orig/arch/i386/kernel/traps.c
+++ 2.6.13a/arch/i386/kernel/traps.c
@@ -804,8 +804,9 @@ void math_error(void __user *eip)
cwd = get_fpu_cwd(task);
swd = get_fpu_swd(task);
switch (swd & ~cwd & 0x3f) {
- case 0x000:
- default:
+ case 0x000: /* No unmasked exception */
+ return;
+ default: /* Multiple exceptions */
break;
case 0x001: /* Invalid Op */
/*
__
Chuck

2005-09-13 20:47:09

by Ondrej Zary

Subject: Re: [patch 2.6.13] i386: Ignore masked FPU exceptions

Chuck Ebbert wrote:
> I think ignoring masked FPU exceptions on i386 is the right thing to do.
> Although there is no documentation available for Cyrix MII, I did find
> erratum F-7 for Winchip C6, "FPU instruction may result in spurious
> exception under certain conditions" which seems to indicate that this can
> happen.
>
> Ondrej, this patch on top of 2.6.13 should fix your Cyrix problems.
> Can you confirm? There was another bug which was already fixed,
> so this should be all that's needed now.

Thanks, it seems to work fine:

rainbow@pentium:~$ ./mprime
Main Menu

1. Test/Primenet
2. Test/User Information
3. Test/Vacation or Holiday
4. Test/Status
5. Test/Continue
6. Test/Exit
7. Advanced/Test
8. Advanced/Time
9. Advanced/P-1
10. Advanced/ECM
11. Advanced/Priority
12. Advanced/Manual Communication
13. Advanced/Unreserve Exponent
14. Advanced/Quit Gimps
15. Options/CPU
16. Options/Preferences
17. Options/Torture Test
18. Options/Benchmark
19. Help/About
20. Help/About PrimeNet Server
Your choice: 17

Beginning a continuous self-test to check your computer.
Please read stress.txt. Hit ^C to end this test.
Test 1, 400 Lucas-Lehmer iterations of M19922945 using 1024K FFT length.
Self-test 1024K passed!
Test 1, 1000 Lucas-Lehmer iterations of M164865 using 8K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M172031 using 8K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M157695 using 8K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M159745 using 8K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M163839 using 8K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M150529 using 8K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M153599 using 8K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M155649 using 8K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M141311 using 8K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M143361 using 8K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M147455 using 8K FFT length.
Test 12, 1000 Lucas-Lehmer iterations of M135169 using 8K FFT length.
Test 13, 1000 Lucas-Lehmer iterations of M136191 using 8K FFT length.
Test 14, 1000 Lucas-Lehmer iterations of M139265 using 8K FFT length.
Test 15, 1000 Lucas-Lehmer iterations of M129023 using 8K FFT length.
Test 16, 1000 Lucas-Lehmer iterations of M131073 using 8K FFT length.
Test 17, 1000 Lucas-Lehmer iterations of M133119 using 8K FFT length.
Test 18, 1000 Lucas-Lehmer iterations of M117761 using 8K FFT length.
Test 19, 1000 Lucas-Lehmer iterations of M121855 using 8K FFT length.
Self-test 8K passed!
Test 1, 1000 Lucas-Lehmer iterations of M215041 using 10K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M204799 using 10K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M208897 using 10K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M212991 using 10K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M194561 using 10K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M196607 using 10K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M200705 using 10K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M184319 using 10K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M186369 using 10K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M188415 using 10K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M164865 using 10K FFT length.
Test 12, 1000 Lucas-Lehmer iterations of M172031 using 10K FFT length.
Test 13, 1000 Lucas-Lehmer iterations of M180225 using 10K FFT length.
Test 14, 1000 Lucas-Lehmer iterations of M157695 using 10K FFT length.
Test 15, 1000 Lucas-Lehmer iterations of M159745 using 10K FFT length.
Test 16, 1000 Lucas-Lehmer iterations of M163839 using 10K FFT length.
Test 17, 1000 Lucas-Lehmer iterations of M150529 using 10K FFT length.
Test 18, 1000 Lucas-Lehmer iterations of M153599 using 10K FFT length.
Self-test 10K passed!
Test 1, 400 Lucas-Lehmer iterations of M17825793 using 896K FFT length.
Self-test 896K passed!
Test 1, 400 Lucas-Lehmer iterations of M14942209 using 768K FFT length.
Self-test 768K passed!
Test 1, 1000 Lucas-Lehmer iterations of M243713 using 12K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M245759 using 12K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M258049 using 12K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M229375 using 12K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M233473 using 12K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M235519 using 12K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M215041 using 12K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M221183 using 12K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M225281 using 12K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M204799 using 12K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M208897 using 12K FFT length.
Test 12, 1000 Lucas-Lehmer iterations of M212991 using 12K FFT length.
Test 13, 1000 Lucas-Lehmer iterations of M194561 using 12K FFT length.
Test 14, 1000 Lucas-Lehmer iterations of M196607 using 12K FFT length.
Test 15, 1000 Lucas-Lehmer iterations of M200705 using 12K FFT length.
Test 16, 1000 Lucas-Lehmer iterations of M184319 using 12K FFT length.
Test 17, 1000 Lucas-Lehmer iterations of M186369 using 12K FFT length.
Test 18, 1000 Lucas-Lehmer iterations of M188415 using 12K FFT length.
Test 19, 1000 Lucas-Lehmer iterations of M164865 using 12K FFT length.
Test 20, 1000 Lucas-Lehmer iterations of M172031 using 12K FFT length.
Self-test 12K passed!
Test 1, 1000 Lucas-Lehmer iterations of M286719 using 14K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M294913 using 14K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M301055 using 14K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M272385 using 14K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M278527 using 14K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M282625 using 14K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M262143 using 14K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M266241 using 14K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M270335 using 14K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M243713 using 14K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M245759 using 14K FFT length.
Test 12, 1000 Lucas-Lehmer iterations of M258049 using 14K FFT length.
Test 13, 1000 Lucas-Lehmer iterations of M229375 using 14K FFT length.
Test 14, 1000 Lucas-Lehmer iterations of M233473 using 14K FFT length.
Test 15, 1000 Lucas-Lehmer iterations of M235519 using 14K FFT length.
Test 16, 1000 Lucas-Lehmer iterations of M215041 using 14K FFT length.
Self-test 14K passed!
Test 1, 400 Lucas-Lehmer iterations of M12451841 using 640K FFT length.
Self-test 640K passed!
Test 1, 400 Lucas-Lehmer iterations of M10223617 using 512K FFT length.
Self-test 512K passed!
Test 1, 1000 Lucas-Lehmer iterations of M344065 using 16K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M319487 using 16K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M327681 using 16K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M329727 using 16K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M307201 using 16K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M311295 using 16K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M315393 using 16K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M286719 using 16K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M294913 using 16K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M301055 using 16K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M272385 using 16K FFT length.
Test 12, 1000 Lucas-Lehmer iterations of M278527 using 16K FFT length.
Test 13, 1000 Lucas-Lehmer iterations of M282625 using 16K FFT length.
Test 14, 1000 Lucas-Lehmer iterations of M262143 using 16K FFT length.
Test 15, 1000 Lucas-Lehmer iterations of M266241 using 16K FFT length.
Self-test 16K passed!
Test 1, 1000 Lucas-Lehmer iterations of M417791 using 20K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M425985 using 20K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M430079 using 20K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M393217 using 20K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M401407 using 20K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M409601 using 20K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M372735 using 20K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M376833 using 20K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M389119 using 20K FFT length.
Test 10, 1000 Lucas-Lehmer iterations of M344065 using 20K FFT length.
Test 11, 1000 Lucas-Lehmer iterations of M360447 using 20K FFT length.
Self-test 20K passed!
Test 1, 400 Lucas-Lehmer iterations of M8716289 using 448K FFT length.
Self-test 448K passed!
Test 1, 400 Lucas-Lehmer iterations of M7471105 using 384K FFT length.
Test 2, 400 Lucas-Lehmer iterations of M7471103 using 384K FFT length.
Self-test 384K passed!
Test 1, 1000 Lucas-Lehmer iterations of M491521 using 24K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M466943 using 24K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M471041 using 24K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M487423 using 24K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M442369 using 24K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M450559 using 24K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M458753 using 24K FFT length.
Test 8, 1000 Lucas-Lehmer iterations of M417791 using 24K FFT length.
Test 9, 1000 Lucas-Lehmer iterations of M425985 using 24K FFT length.
Self-test 24K passed!
Test 1, 1000 Lucas-Lehmer iterations of M589823 using 28K FFT length.
Test 2, 1000 Lucas-Lehmer iterations of M557057 using 28K FFT length.
Test 3, 1000 Lucas-Lehmer iterations of M565247 using 28K FFT length.
Test 4, 1000 Lucas-Lehmer iterations of M573441 using 28K FFT length.
Test 5, 1000 Lucas-Lehmer iterations of M532479 using 28K FFT length.
Test 6, 1000 Lucas-Lehmer iterations of M540673 using 28K FFT length.
Test 7, 1000 Lucas-Lehmer iterations of M544767 using 28K FFT length.
Self-test 28K passed!
Test 1, 400 Lucas-Lehmer iterations of M6422529 using 320K FFT length.
Test 2, 400 Lucas-Lehmer iterations of M6422527 using 320K FFT length.
Self-test 320K passed!
Test 1, 400 Lucas-Lehmer iterations of M5242881 using 256K FFT length.
Torture Test ran 6 hours, 6 minutes - 0 errors, 0 warnings.


> Signed-off-by: Chuck Ebbert <[email protected]>
>
> arch/i386/kernel/traps.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> --- 2.6.13a.orig/arch/i386/kernel/traps.c
> +++ 2.6.13a/arch/i386/kernel/traps.c
> @@ -804,8 +804,9 @@ void math_error(void __user *eip)
> cwd = get_fpu_cwd(task);
> swd = get_fpu_swd(task);
> switch (swd & ~cwd & 0x3f) {
> - case 0x000:
> - default:
> + case 0x000: /* No unmasked exception */
> + return;
> + default: /* Multiple exceptions */
> break;
> case 0x001: /* Invalid Op */
> /*
> __
> Chuck
>


--
Ondrej Zary