DMA test hangs the computer

[Sunspark]

Hi, with 9.5b1 test 14 DMA, it freezes my older system at 10%. The memory passes 1-13 with no errors and none are shown for DMA either, it just hard freezes at 10%. This is with a USB flash drive. I tried it with both the USB 3.0 and 2.0 buses, no change.

The light stops flashing, there is no mouse cursor and the keyboard does not respond.

I saw in another thread that the issue might be due to a uefi issue with greater than 32 bit addresses. There are 2 8-gig sticks for a total of 16 GB so I'm not sure this makes sense here because the 32 bit limit is 4 GB and 10% at the freeze mark is below that.

[David (PassMark)]

There is a chance it is a bad flash drive. Do you have another one to try?

Otherwise can you provide a debug log file.
https://www.memtest86.com/tech_debug-logs.html

[Sunspark]

I am skeptical it is the drive because I routinely write a whole os image to it but I could try another cheap one or a SD card just to see and also to see if the same problem as below happens again.

There is a bigger issue now tho which was unexpected. After I did that DMA test yesterday Win 10 stopped booting with a kmode stop mode exception bluescreen reboot. Putting the old ram sticks back in the machine didn't resolve it. The behaviour was worse than just the OS in the partition. Win10 based boots from USB like Macrium rescue etc also failed with the same error and resetting cmos battery didn't stop it. I ended up having to dig out a 2015 win10 image to install to a partition and then I was able to use the macrium USB without error to restore the backup from a week ago but better than never. I have never seen this before where something on the OS partition was preventing external drives that were win10 based from being able to boot. Win 7 and Linux on the machine were fine of course.

[Sunspark]

There is a chance it is a bad flash drive. Do you have another one to try?

Otherwise can you provide a debug log file.
https://www.memtest86.com/tech_debug-logs.html

Hi, I have an update on this.

First, a recommendation. By all means, include the DMA test in 9.5, but I recommend that it be disabled by default based on the trouble I've had and other people seem to have had issues as well.

After disassembling and resetting the computer last night, I decided to test again as per your suggestion using an old slow USB flash drive that I only use as a throwaway for stuff I don't care about. The one I was using the night before was a faster SLC chip drive.

Much to my surprise, the DMA test went past 10% on the old junky drive and I got the green PASS. RAM is good, hooray! Must have been the drive.. not so fast!

I did further testing.. having established that it is possible to pass the DMA test, I went into the bios and turned off some settings: Intel VT for Directed I/O (VT-D), Virtualization Technology, Wake on LAN, PCIe ASPM Support, Network Boot, Optical Boot.

Went back into Memtest86.. first observation.. the #s reported for L1 Cache, L2 Cache, L3 Cache and Memory were lower than before I turned off the options. This was not expected.

Using the same DMA test, tested again.. it froze at 10% just like the night before.

Turned on 2 of the 6 options, tested.. #s still low, still froze at 10%.

Turned on a 3rd option, tested.. #s still low, still froze at 10%.

Turned on the remaining 3 of the 6 for all 6 back on, tested.. #s STILL remained low, still froze at 10%.

The behaviour on the freeze was strange.. holding down the power button to force the computer to shut down, the power light would go out and the fan would shut down, but the USB flash drive would CONTINUE flashing the LED..

Disassembled the machine and pulled the CMOS battery again. After 20 minutes put it back in. Weirdly, while the clock/date was reset and the log indicated that the CMOS was blanked, the other settings were not actually reset to system defaults but that was fine.

Booted back into Memtest86, L1,L2,L3 and Memory were back at the #s for GB/s I expected to see. I didn't run the DMA test again since I already know it passed and I don't want to have to disassemble the board every time there is an issue.

So, the test works, but beyond that of possible issues with drives, there are additional issues involving system bios settings. It was strange to me that changing some settings made a sticky change to bandwidth recorded by Memtest86 that couldn't be undone except w/o a battery pull. I have a feeling other people may have shaky BIOs configs as well. My suspicion is that there's something glitchy involving the VT-D & Virtualization setting. I don't think it was the PCIe ASPM or boot options.

The bios and board here is from Intel so pretty mainstream.

[Sunspark]

Couldn't resist. Turned off pcie aspm, it failed. Turned it back on, still fails at 10%. Pulled battery & passed, but the L1-Mem numbers are lower again. Pulled battery again hopefully they will be back up again in an hour.

[David (PassMark)]

After I did that DMA test yesterday Win 10 stopped booting with a kmode stop mode exception bluescreen reboot.

I suspect this is co-incidence and not causation. The DMA test just reads and writes data to the flash drive. It doesn't do any tricky reconfiguration of the system.

Send the debug log file for the lockup case, if you want.
https://www.memtest86.com/tech_debug-logs.html