64bit Prime95 25.11.2 finds the correct factors on Windows XP 64bit.

[quote=__HRB__;216534]What happens if you boot using a 64-bit live-CD from a different distro, run mprime (should have no errors), chroot, and run mprime again?[/quote]


Using the previous Ubuntu 9.10 disc, I mounted the local partition and tested one of the exponents; mprime returned the correct factor. When I chroot and run it again, mprime returns the incorrect factor.

[quote=lindee;216725]Using the previous Ubuntu 9.10 disc, I mounted the local partition and tested one of the exponents; mprime returned the correct factor. When I chroot and run it again, mprime returns the incorrect factor.[/quote]

[quote=__HRB__;216680]My bottom dollar is on a bug in a shared library in the (or your) Ubuntu installation/configuration.[/quote]

Maybe I should leverage my bottom dollar. :-)

Just created a virtual machine (on different hardware) and did a fresh install of Ubuntu 10.04 64-bit. The problem exists here as well.

[quote=lindee;216731]Just created a virtual machine (on different hardware) and did a fresh install of Ubuntu 10.04 64-bit. The problem exists here as well.[/quote]
Could you do a similar test with 9.10 or earlier(earlier than 8.04 would be a bit early)?

I performed the same test on the VM as suggested by _HRB_ and the results were the same as the original problem PC. Booting into Ubuntu 9.10 and running mprime found the correct factor. Doing a chroot to the Ubuntu 10.04 installation resulted in mprime returning the wrong factor.

I am currently downloading the 32-bit version of Ubuntu 10.04 to see whether or not this bug is limited to just the 64-bit version.

[quote=lindee;216951]I performed the same test on the VM as suggested by _HRB_ and the results were the same as the original problem PC. Booting into Ubuntu 9.10 and running mprime found the correct factor. Doing a chroot to the Ubuntu 10.04 installation resulted in mprime returning the wrong factor.

I am currently downloading the 32-bit version of Ubuntu 10.04 to see whether or not this bug is limited to just the 64-bit version.[/quote]
sorry i didn't notice you had tried 9.10
comes of being away for a couple of weeks

On the 32-bit Ubuntu 10.04, mprime found the correct factor.

ditto.
 

[quote=lindee;216490]One of my machines seems to have been reporting invalid factors for several exponents for about the past week.

[...]

Problem machine is Core2Quad running mprime 25.11 64-bit on Ubuntu 10.04. I think the problem started last Friday either during or after upgrading Ubuntu.

Has anyone else seen anything like this?



Addition: There is a pattern with the invalid factors. In the last seven digits of each invalid factor, the last three digits are always the same and the first three are always the same.[/quote]

Same problem here. Q6600, Ubuntu Lucid x64, mprime 25.11 x64.

83 exponents affected over the last 43 days. Range=90-91M, depth=64-65 bits.

Will rerun those expos under Windoze as resources permit.



Cheers,

Carsten

No need to rerun them; the first sixteen-or-so digits are right and you know the value has to be 1 mod p, so a very quick search around the wrong answer will give the right one. Post exponents and wrong factors here and I will post correct factors

Any volunteers to debug this? Look in the gtoc routine in gwnum/giants.c