[LLVMdev] LLVM on OpenBSD

[Mike Stump]

On Jun 18, 2008, at 6:08 AM, Edd Barrett wrote:
> Sometimes you get a clean build of llvm, sometimes you don't and  
> instead
> get a bus error.

gcc makes a excellent systems test.  Try this, while :; do make  
boostrap && make clean; done with the FSF top of tree gcc.  Let it run  
for 2 weeks.  If it ever built once, it should never fail to build.   
If it does, I'd install a good linux distribution on the same hardware  
and try again, if it still fails, look to replace the hardware. If  
linux works, I'd look to replace the OS.  If it failed everytime in  
the exact same spot in the exact same way, try the last FSF release  
for gcc.

If it fails deterministically, that could be a gcc bug (or very bad  
hardware).  If it fails non-deterministically, you're most likely  
looking at bad hardware.

> That is one reason a bus error might occur, but my more common
> understanding of a bus error is data not properly aligned with the  
> byte
> boundaries and/or out of range memory at the physical level.

Absent a bad version of gcc and a bad OS, the usual culprit is bad  
hardware.

> The machine I am building on is my workstation which I use 9-4.30
> mon-fri. I run all manner of apps without any problems, so if it were
> bad hardware it would have shown itself by now surely.

No.  I've seen machines that work flawlessly, pass all manner of  
memory tests including 24+ hours of standalone memtest86, right up to  
the point you ask them to boostrap gcc, then they fail, 100% of the  
time.  Find someone with good hardware, same OS.  See if the testcase  
that fails for you, fails for them.  Try and use the same gcc binaries  
for the test.  If it passes for someone else, again, probably bad  
hardware.

If you live in California, I'd ask if you bought you memory at Fry's?   
They test all their memory to ensure it is bad, unless you buy the  
namebrand memory.  :-(