Illegal instruction for sandybridge subarch

[prof]

Hi all,

 

I carefully reviewed my CPU info and googled to see the proper architecture

Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz

That points to  intel64-sandybridge

However, using that architecture I receive "Illegal instruction" error during various steps (e.g. compiling cups or running NetworkManager)

I do not want to be "too safe" and choose a generic architecture. Could you please point to the right one closest to that particular CPU?

 

Thank you

[prof]

Well, maybe I started the topic from the wrong question.

 

Does getting "Illegal instruction" message have a most possible cause of choosing a wrong subarchitecture at first place?

 

Response much appreciated.

[Tassie_Tux]

I too would have chosen intel64-sandybridge. Your issues are either more complicated than simply your choice in subarch, or are indeed related to some other factor.

 

For compilation issues I encourage you to report them on bugs.funtoo.org (see http://www.funtoo.org/Reporting_Bugs). When you do you will need to attach supporting information such as the output of 'emerge --info' and the particular package's build.log. The effort is however worth it as reporting like this is arguably the best way to receive timely assistance with build failures.

 

As for the "illegal instruction" messages when running a successfully merged package, I would say in the first instance that more information is going to be required to assist you. Additionally, the information required will depend on the package causing problems for you.

[prof]

Besides getting intel64-sandybridge stage3 file, I have also set variables:

 

CHOST x86_64-pc-linux-gnu CFLAGS -march=corei7-avx -O2 -pipe

 

I do not think it is a good idea to bother cups/networkmanager/other package developers/maintainers, because that does not appear to be package specific. I would say systemwide instead.

 

I removed everything and started from scratch, going back one step to intel64-nehalem subarch (with a corresponding CFLAGS change), all illegal instructions have gone like a magic.

 

So to summarize, I know how to fix it, but have no idea why it did not work with an original configuration. Thanks.

[lockie]

Just stumbled upon illegal instruction on sandybridge too. The trick (for me at least) was in incorrect set of CPU flags, including aes which is not available on my i3-2100 (see this post http://forums.funtoo.org/topic/868-question-about-use-flags/?p=4318for how to set CPU flags correctly).

[Oleg Vinichenko]

where does "Illegal instruction" happen? need logs. But i suspect its a segfault in nettle, which is due to AES instruction. If your CPU not supporting it, you need to disable it. Know thy hardware :).

[paddymac]

I have to agree with Oleg that, if you're going to run a source-based distro, you should be familiar with your hardware. Are you getting the errors during compilation or during runtime? Generally if you're compiling software with cpu flags your processor doesn't recognize, the error will appear when you attempt to run the program -- not during compilation. I've seen the error plenty of times since I use some old hardware that doesn't support sse2 which is often required nowadays.

[prof]

Sorry about necromancing an ancient topic, I gave up and falled back to an older intel64-nehalem architecture, no illegal instructions. Some documentation which says my CPU is sandybridge seemed to be just plain wrong.

P.S. "Knowing thy hardware" sounds good, I'd love to do that, but since I did not design the CPU, I had to rely on Internet to identify that.

Edited November 30, 2022 by prof