gcc and kernel build trouble report

From: Keith Mannthey
Date: Fri Mar 12 2010 - 18:38:14 EST


Hello,

At the start of the week I moved kernels forwarded. I tried
2.6.34-rc1 and 2.6.33-git15. The lpfc fiber channel driver was failing
to load and generating a hardware level pci bus fault that was resetting
the server. There is a small thread on linux-scsi from when I started.

Tried forward porting know working versions of the driver to the new
kernels but it did not fix the problem. I have to reason to suspect the
actual code in the driver is not really involved with the issue.

I booted whole older kernels until I sorted out that somewhere post
2.6.33 stock that issue started. I am not 100% sure where in the kernel
commits the problem starts I just know if is after 2.6.33.

It was identified that an alternate .config file worked and I decided
to dig on the config options.

I narrowed the config change down to:

CONFIG_CC_OPTIMIZE_FOR_SIZE

I have to set CONFIG_CC_OPTIMIZE_FOR_SIZE=y else I get a pci fault
while failing to load the lpfc driver. As I understand this passes a
different -O flag to the build.


Relevant details:

Hardware: IBM x3550m2 server. Current Intel based 2 socket system,
nothing fancy.

GCC: gcc version 4.3.4 [gcc-4_3-branch revision 152973] (SUSE Linux)

Kernels: For sure, 2.6.34-rc1, 2.6.33-git15 have the problem. If the 10
or so 2.6.33 and before kernels trees I have booted I did not encounter
the issue.

Config: CONFIG_CC_OPTIMIZE_FOR_SIZE=y or bad things happen. I booted a
ton of .config changes, 100% sure this is it, it has been triple
checked.

All in all not a fun experience and I don't really have the skills to
fix this issue. I am going to try a different gcc version when I get a
few cycles.

Any suggestions on what to do with this gcc / kernel build issue? I
found it a little unsettling.

Thanks,
Keith Mannthey
LTC FS-Dev





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