>Number: 173337
>Category: kern
>Synopsis: clang kernel cross-builds ignore CPUTYPE?= and always generate
>native tuned code
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Nov 03 20:40:00 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Howard Goldstein
>Release:
>Organization:
>Environment:
Oct 30 13:45:20 pickle kernel: FreeBSD 9.1-PRERELEASE #13: Thu Oct 25 22:29:56 E
DT 2012
Oct 30 13:45:20 pickle kernel: [email protected]:/usr/obj/usr/src/sys/PICKLE
i3
86
Oct 30 13:45:20 pickle kernel: CPU: Intel(R) Core(TM)2 Duo CPU E6750 @ 2.66
GHz (2667.76-MHz 686-class CPU)
Oct 30 13:45:20 pickle kernel: Origin = "GenuineIntel" Id = 0x6fb Family = 0x6
Model = 0xf Stepping = 11
Oct 30 13:45:20 pickle kernel: Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MC
>Description:
Kernel compiled on a system id'd as a core2 a/k/a nocona in i386 mode (above)
and stock clang of 9.1 prerelease 13:
pickle:~$ clang -v
FreeBSD clang version 3.1 (branches/release_31 156863) 20120523
Target: i386-unknown-freebsd9.0
Thread model: posix
for a i386 for a pentium4 both i386 with these set in make.conf
CPUTYPE?=pentium4
CC=clang
CXX=clang++
CPP=clang-cpp
The resulting kernel seems to actually be built for the host
as if -march=native were set, ignoring CPUTYPE?=pentium4
This is almost surely the same problem reported on -stable by
Volodymyr Kostyrko c.kworr on Wed Oct 24 07:57:26 UTC 2012
at http://lists.freebsd.org/pipermail/freebsd-stable/2012-October/070228.html
>How-To-Repeat:
Build a kernel with clang on a host that is, for lack of a better expression
"stronger" than your handy, "lesser" target. For ex., a core2 host targetting
a pentium-m.
Now install emulators/wine or emulator/wine-devel, built however you
like. The wine process handles its own trapping which makes this very
difficult to identify (for me, anyway) as a kernel issue:
err:seh:raise_exception Unhandled exception code c0000005 flags 0 addr 0x622...
and wine opens a black window and hangs up.
>From gdb it's a bit more verbose and yields a map file error.
This is probably impossible to reproduce without a separate target system
real or virtual that doesn't support the instruction set of the build host.
>Fix:
Revert to stock gcc4.2 for crossbuilding 9.1 kernels destined for
a specific CPUTYPE that doesn't match the host
This PR may belong in conf or ports instead of kern, please recategorize
>Release-Note:
>Audit-Trail:
>Unformatted:
Release: FreeBSD 9.1-PRERELEASE i386
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