On Tue, Sep 1, 2015 at 12:48 AM, Liu Ting <ting....@freescale.com> wrote: > When trying to use gcc-linaro-4.9 to build u-boot for ls1021atwr (ARM > Cortex-A7 MPCore compliant with ARMv7-A architecture), we face issue. U-boot > hangs at PCI-E. > > After tracing the code, the issue is located at the line “*val = > readl(addr);”. > > u-boot/drivers/pci/pcie_layerscape.c: ls_pcie_read_config(): >
> After Bisecting, we tracked down a gcc commit: > https://git.linaro.org/toolchain/gcc.git/commitdiff/e4f9e85e8152379aef373772b22075539920ffa2?hp=da278625cc33cbbc893cc50c2ac32fca31053ee8 > 2015-01-23 Jakub Jelinek <ja...@redhat.com> > PR rtl-optimization/63637 > PR rtl-optimization/60663 > * cse.c (merge_equiv_classes): Set new_elt->cost to MAX_COST > ... It is hard to look at a compiler issue when I can't reproduce the problem. You gave good info about the compiler, but you didn't point at u-boot sources. i tried git clone http://git.linaro.org/boot/u-boot-linaro-stable.git but there is no pcie_layerscape.c file. The problem fixed by the patch can be seen here https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63637 A description of the patch can be found in the submission email here: https://gcc.gnu.org/ml/gcc-patches/2015-01/msg00894.html There are testcases in the patch that show what it does. The patch allows the compiler to optimize away redundant extended asm statements via common subexpression elimination (CSE), when the asm statements aren't volatile, don't have multiple outputs, and don't have memory clobbers. If this is breaking your code, then it appears that you are missing a volatile declaration or extended asm memory clobber somewhere. I don't have the code to look at, so I can't suggest what might be wrong with the code. Jim _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org https://lists.linaro.org/mailman/listinfo/linaro-toolchain
