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In banked-sr.c, we use a top-level '__asm__(".arch_extension virt")'
statement to allow compilation of a multi-CPU kernel for ARMv6
and older ARMv7-A that don't normally support access to the banked
registers.
This is considered to be a programming error by the gcc developers
and will no longer work in gcc-8, where we now get a build error:
/tmp/cc4Qy7GR.s:34: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_usr'
/tmp/cc4Qy7GR.s:41: Error: Banked registers are not available with this architecture. -- `mrs r3,ELR_hyp'
/tmp/cc4Qy7GR.s:55: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_svc'
/tmp/cc4Qy7GR.s:62: Error: Banked registers are not available with this architecture. -- `mrs r3,LR_svc'
/tmp/cc4Qy7GR.s:69: Error: Banked registers are not available with this architecture. -- `mrs r3,SPSR_svc'
/tmp/cc4Qy7GR.s:76: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_abt'
Passign the '-march-armv7ve' flag to gcc works, and is ok here, because
we know the functions won't ever be called on pre-ARMv7VE machines.
Unfortunately, older compiler versions (4.8 and earlier) do not understand
that flag, so we still need to keep the asm around.
Backporting to stable kernels (4.6+) is needed to allow those to be built
with future compilers as well.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84129
Fixes:
|
||
|---|---|---|
| .. | ||
| hyp | ||
| coproc_a7.c | ||
| coproc_a15.c | ||
| coproc.c | ||
| coproc.h | ||
| emulate.c | ||
| guest.c | ||
| handle_exit.c | ||
| init.S | ||
| interrupts.S | ||
| irq.h | ||
| Kconfig | ||
| Makefile | ||
| reset.c | ||
| trace.h | ||
| vgic-v3-coproc.c | ||