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Diffstat (limited to 'arch/arm/Kconfig')
| -rw-r--r-- | arch/arm/Kconfig | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 2fec7073f68..f871f2e1dd7 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1379,6 +1379,37 @@ config THUMB2_KERNEL If unsure, say N. +config THUMB2_AVOID_R_ARM_THM_JUMP11 + bool "Work around buggy Thumb-2 short branch relocations in gas" + depends on THUMB2_KERNEL && MODULES + default y + help + Various binutils versions can resolve Thumb-2 branches to + locally-defined, preemptible global symbols as short-range "b.n" + branch instructions. + + This is a problem, because there's no guarantee the final + destination of the symbol, or any candidate locations for a + trampoline, are within range of the branch. For this reason, the + kernel does not support fixing up the R_ARM_THM_JUMP11 (102) + relocation in modules at all, and it makes little sense to add + support. + + The symptom is that the kernel fails with an "unsupported + relocation" error when loading some modules. + + Until fixed tools are available, passing + -fno-optimize-sibling-calls to gcc should prevent gcc generating + code which hits this problem, at the cost of a bit of extra runtime + stack usage in some cases. + + The problem is described in more detail at: + https://bugs.launchpad.net/binutils-linaro/+bug/725126 + + Only Thumb-2 kernels are affected. + + Unless you are sure your tools don't have this problem, say Y. + config ARM_ASM_UNIFIED bool |