[SOLVED] Stable gentoo kernel in Vortex86DX

BlackLodge · Last edited by BlackLodge on Mon Apr 19, 2021 8:29 pm; edited 2 times in total

This is a continuation for this thread.

Vortex86DX is a 486 clone running at MHz. It should run any binary compiled for intel x86, however it does have "some" issues.

I managed to compile a 32 bits gentoo system that boots and runs stable enough to ssh the machine. However, under heavy IO load with the ethernet, or the hard drive, the kernel crash is almost guaranteed. Some examples:

SCP a file:

eccerr0r · Posted: Thu Apr 15, 2021 11:04 pm Post subject:

Looks like you didn't post the dmesg and posted .config twice?

Anyway how did you build your kernel?

It looks like DM&P have their own distribution and I'm not sure if they got their changes incorporated into mainline, or did they?

You getting an invalid opcode indicates that your build toolchain or hardcoded assembly got incorporated into the kernel and the processor is barfing on it...
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Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

BlackLodge · Posted: Fri Apr 16, 2021 10:22 am Post subject:

eccerr0r · Posted: Fri Apr 16, 2021 3:29 pm Post subject:

"should" and "does" are two different things...

Seems to be some flakiness in the CPU possibly or handles things like DMA improperly, don't know if there are options to underclock the cpu or not, it may change the behavior.
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

BlackLodge · Posted: Mon Apr 19, 2021 8:13 pm Post subject:

NeddySeagoon · Posted: Mon Apr 19, 2021 8:30 pm Post subject:

BlackLodge,

That runs the CPU more slowly. That gives everything longer to settle before it changes again.

BlackLodge · Posted: Mon Apr 19, 2021 8:53 pm Post subject:

Yes you are right, currently:

NeddySeagoon · Posted: Mon Apr 19, 2021 9:48 pm Post subject:

This link says

BlackLodge · Posted: Wed Apr 21, 2021 7:50 am Post subject:

Thanks Neddy.

I think I found something interesting too, take a look to the "Programming reference" from their website here.

The CPU speed can be controlled by writing / reading to some register of the Northbridge. I think this is what the BIOS does with the "Divide by X".

I will try this as soon as I have some time. Also, I am thinking about the possibility of writing a little kernel module for using this as a way to dinamically change CPU speed with gobernors, as already said. I find the gap between 933 MHz and 466 MHz too big, I wonder if it is possible to operate in 933 until some condition, then downclock the CPU to prevent crashes. Will see.

D*wn this thing is such a toy.

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Installing gentoo in a Vortex86DX

Kernel: https://forums.gentoo.org/viewtopic-t-1133787.html
CFLAGS, CHOST: https://forums.gentoo.org/viewtopic-t-1130400.html

NeddySeagoon · Posted: Wed Apr 21, 2021 12:48 pm Post subject:

BlackLodge,

The hardware data sheet says that the clock speed is set by using some of the MA (memory address) pins.
Clearly that can't be done after reset, as they will be used for addressing memory. :)
Externally to the CPU the clock will be generated by a PLL and that can be set under CPU control ... maybe.

There are 16 different settings for the CPU clock in the datasheet, so I'm surprised that the BIOS only gives a choice of too fast and too slow :)

Computers have always been fun to play with. I started in 1963 :)
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

BlackLodge · Posted: Thu Apr 22, 2021 9:14 am Post subject: