[lfs-dev] kernel messages during gcc tests

ALZ (phyglos.org) alz at phyglos.org
Wed Feb 3 10:47:24 PST 2016

Hi Bruce, all,

I'm also updating my scripts to last versions. Here, my two cents.

On 02/03/2016 05:36 AM, Bruce Dubbs wrote:
> I just updated several packages in LFS and did a complete LFS build
> including all Chapter 6 tests.One thing I noticed that I haven't seen
> before is a ton of error messages in /var/log/kern.log.  The look like:
> Feb  2 20:52:05 lfs78 kernel: [1888937.495544] lib-42.exe[6559]:
> segfault at 8 ip 00007f63a68c1fbe sp 00007fffd02bbde0 error 4 in
> libgomp.so.1.0.0[7f63a68ab000+1f000]

I've noticed some random failures at different tests from GCC in several 
runs of my scripts (probably after upgrading to gcc 5.3.0, but I cannot 
confirm anything). I'm building with all tests switched on in all packages.

Here is the first example of what I've found in /var/log>/kern.log after 
reading your message.

Jan 30 10:09:12 PCALZ8phy kernel: [128479.612812] lib-42.exe[10783]: 
segfault at 8 ip 00007f0d2eff4ffe sp 00007ffeadf9f880 error 4 in 

> In addition to segfaults, there are some messages about 'trap invalid
> opcode' in overflow-add-4.exe.

Feb  2 21:13:05 PCALZ8phy kernel: [49354.387702] traps: 
overflow-add-4.[20088] trap invalid opcode ip:400683 sp:7ffde7b954d8 
error:0 in overflow-add-4.exe[400000+1000]

>  From the time stamps, I traced these to the gcc testuite.  The test log
> does not show anything unusual.  There are two unexpected failures in
> libstdc++:
> FAIL: experimental/filesystem/iterators/directory_iterator.cc
> FAIL: experimental/filesystem/iterators/recursive_directory_iterator.cc

Libstdc++ are the random, unexpected failures at GCC tests that caught 
my attention but I was just focusing in updating my scripts.

> But I've seen those before.
> Overall the build seems to have been normal.

I once had a total freeze of my VM and had to revert back to a stable 
snapshot to continue updating. (I remember some "kernel errors" in the 
screen but I didn't jot down anything)

> A couple of things to consider is that it may be a HW issue on my
> system.  It's a new Skylake i5, so gcc may be making the wrong
> assumptions about instruction set.  I can check this out on an Haswell
> i7 to see if it happens there.
> Overall, these may just artifacts in the gcc test procedure, but has
> anyone else seen anything like this?
>    -- Bruce

I'm planning to run full LFS builds this weekend with last packages 
versions both in VM and physical machine. Should this issues repeat 
consistently with the new updated scripts, I'll report back.


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