Il 14/03/2013 16:25, Peter Maydell ha scritto:
> The gthread coroutine backend is broken and does not produce a working
> QEMU; it is only useful for some very limited debugging situations.
> Clean up the backend selection logic in configure so that it now runs
> "if on windows use windows; else prefer ucontext; else sigaltstack".
>
> To do this we refactor the configure code to separate out "test
> whether we have a working ucontext", "pick a default if user didn't
> specify" and "validate that user didn't specify something invalid",
> rather than having all three of these run together. We also have to
> adjust the Makefile logic so it doesn't also encode an idea of the
> default backend.
You need to fix also tests/Makefile (don't mention it, I missed the boat
for reviewing the patch on qemu-devel).
Perhaps it's simpler to export a single CONFIG_COROUTINE_BACKEND symbol
from configure to the Makefile? (This way patch 2 also becomes
unnecessary).
Patch 1 looks good.
Thanks,
Paolo
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> Makefile.objs | 6 +++---
> configure | 67
> +++++++++++++++++++++++++++++++++++++--------------------
> 2 files changed, 47 insertions(+), 26 deletions(-)
>
> diff --git a/Makefile.objs b/Makefile.objs
> index f99841c..7f541a4 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -18,12 +18,12 @@ block-obj-y += qemu-coroutine.o qemu-coroutine-lock.o
> qemu-coroutine-io.o
> block-obj-y += qemu-coroutine-sleep.o
> ifeq ($(CONFIG_UCONTEXT_COROUTINE),y)
> block-obj-$(CONFIG_POSIX) += coroutine-ucontext.o
> -else
> +endif
> ifeq ($(CONFIG_SIGALTSTACK_COROUTINE),y)
> block-obj-$(CONFIG_POSIX) += coroutine-sigaltstack.o
> -else
> -block-obj-$(CONFIG_POSIX) += coroutine-gthread.o
> endif
> +ifeq ($(CONFIG_GTHREAD_COROUTINE),y)
> +block-obj-$(CONFIG_POSIX) += coroutine-gthread.o
> endif
> block-obj-$(CONFIG_WIN32) += coroutine-win32.o
>
> diff --git a/configure b/configure
> index d9dfde0..9f7f5cd 100755
> --- a/configure
> +++ b/configure
> @@ -3052,31 +3052,55 @@ fi
> ##########################################
> # check and set a backend for coroutine
>
> -# default is ucontext, but always fallback to gthread
> -# windows autodetected by make
> -if test "$coroutine" = "" -o "$coroutine" = "ucontext"; then
> - if test "$darwin" != "yes"; then
> - cat > $TMPC << EOF
> +# We prefer ucontext, but it's not always possible. The fallback
> +# is sigcontext. gthread is not selectable except explicitly, because
> +# it is not functional enough to run QEMU proper. (It is occasionally
> +# useful for debugging purposes.) On Windows the only valid backend
> +# is the Windows-specific one.
> +
> +ucontext_works=no
> +if test "$darwin" != "yes"; then
> + cat > $TMPC << EOF
> #include <ucontext.h>
> #ifdef __stub_makecontext
> #error Ignoring glibc stub makecontext which will always fail
> #endif
> int main(void) { makecontext(0, 0, 0); return 0; }
> EOF
> - if compile_prog "" "" ; then
> - coroutine_backend=ucontext
> - else
> - coroutine_backend=gthread
> - fi
> + if compile_prog "" "" ; then
> + ucontext_works=yes
> + fi
> +fi
> +
> +if test "$coroutine" = ""; then
> + if test "$mingw32" = "yes"; then
> + coroutine=windows
> + elif test "$ucontext_works" = "yes"; then
> + coroutine=ucontext
> + else
> + coroutine=sigaltstack
> fi
> -elif test "$coroutine" = "gthread" ; then
> - coroutine_backend=gthread
> -elif test "$coroutine" = "windows" ; then
> - coroutine_backend=windows
> -elif test "$coroutine" = "sigaltstack" ; then
> - coroutine_backend=sigaltstack
> else
> - error_exit "unknown coroutine backend $coroutine"
> + case $coroutine in
> + windows)
> + if test "$mingw32" != "yes"; then
> + error_exit "'windows' coroutine backend only valid for Windows"
> + fi
> + ;;
> + ucontext)
> + if test "$ucontext_works" != "yes"; then
> + feature_not_found "ucontext"
> + fi
> + ;;
> + gthread|sigaltstack)
> + if test "$mingw32" = "yes"; then
> + error_exit "only the 'windows' coroutine backend is valid for Windows"
> + fi
> + ;;
> + *)
> + error_exit "unknown coroutine backend $coroutine"
> + ;;
> + esac
> fi
>
> ##########################################
> @@ -3383,7 +3407,7 @@ echo "OpenGL support $opengl"
> echo "libiscsi support $libiscsi"
> echo "build guest agent $guest_agent"
> echo "seccomp support $seccomp"
> -echo "coroutine backend $coroutine_backend"
> +echo "coroutine backend $coroutine"
> echo "GlusterFS support $glusterfs"
> echo "virtio-blk-data-plane $virtio_blk_data_plane"
> echo "gcov $gcov_tool"
> @@ -3713,11 +3737,8 @@ if test "$rbd" = "yes" ; then
> echo "CONFIG_RBD=y" >> $config_host_mak
> fi
>
> -if test "$coroutine_backend" = "ucontext" ; then
> - echo "CONFIG_UCONTEXT_COROUTINE=y" >> $config_host_mak
> -elif test "$coroutine_backend" = "sigaltstack" ; then
> - echo "CONFIG_SIGALTSTACK_COROUTINE=y" >> $config_host_mak
> -fi
> +def="CONFIG_$(upper $coroutine)_COROUTINE"
> +echo "$def=y" >> $config_host_mak
>
> if test "$open_by_handle_at" = "yes" ; then
> echo "CONFIG_OPEN_BY_HANDLE=y" >> $config_host_mak
>
