Re: [Qemu-devel] [PATCH] tcg: fix --disable-tcg build breakage introduced by tb_lock removal

[Peter Maydell]

On 22 June 2018 at 17:16, Emilio G. Cota <address@hidden> wrote:
> Tested to build x86_64-softmmu and i386-softmmu targets.
>
> Reported-by: Peter Maydell <address@hidden>
> Signed-off-by: Emilio G. Cota <address@hidden>
> ---
>  accel/stubs/tcg-stub.c | 4 ----
>  exec.c                 | 4 ++++
>  2 files changed, 4 insertions(+), 4 deletions(-)

This still doesn't link for me:

  LINK    x86_64-softmmu/qemu-system-x86_64
exec.o: In function `tlb_reset_dirty_range_all':
/home/petmay01/linaro/qemu-from-laptop/qemu/exec.c:1334: undefined
reference to `tlb_reset_dirty'
exec.o: In function `tcg_commit':
/home/petmay01/linaro/qemu-from-laptop/qemu/exec.c:3056: undefined
reference to `cpu_reloading_memory_map'
cpus.o: In function `tcg_cpu_exec':
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1362: undefined
reference to `cpu_exec'
cpus.o: In function `qemu_tcg_rr_cpu_thread_fn':
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1401: undefined
reference to `tcg_register_thread'
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1471: undefined
reference to `cpu_exec_step_atomic'
cpus.o: In function `qemu_tcg_cpu_thread_fn':
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1637: undefined
reference to `tcg_register_thread'
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1673: undefined
reference to `cpu_exec_step_atomic'
cpus.o: In function `qemu_tcg_init_vcpu':
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1865: undefined
reference to `tcg_region_init'
/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1875: undefined
reference to `parallel_cpus'
collect2: error: ld returned 1 exit status

Configured with --target-list=x86_64-softmmu --enable-debug --disable-tcg

It's probably the --enable-debug that makes the difference:
for instance cpu_reloading_memory_map() is referenced from
tcg_commit(), which is only called from within an "if (tcg_enabled())"
guard; with debug disabled the compiler probably figures out that
tcg_commit() is unreachable and doesn't put it in the .o file.

Possibly this has always been broken and wasn't a regression?
If so I guess we should apply your patch and then fix this
separately...

thanks
-- PMM