[v2] util: sync error_report & qemu_log output more closely

[PATCH v2 01/14] include: define constant for early constructor priority

Posted by Daniel P. Berrangé 4 weeks, 1 day ago

Functions marked with __attribute__((__constructor__)) will be
invoked in linker order. In theory this is well defined, but
in practice, it is hard to determine what this order will be
with the layers of indirection through meson, ninja and the
static libraries QEMU builds.

Notably, the order currently appears different between Linux
and Windows (as tested with Wine on Linux). This can cause
problems when certain QEMU constructors have a dependancy on
other QEMU constructors.

To address this define a QEMU_CONSTRUCTOR_EARLY constant which
provides a priority value that will run before other default
constructors. This is to be used for QEMU constructors that
are themselves self-contained, but may be relied upon by other
constructors.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 include/qemu/compiler.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 1c2b673c05..4c49f52eb0 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -194,6 +194,14 @@
 # define QEMU_USED
 #endif
 
+/*
+ * A priority for __attribute__((constructor(...))) that
+ * will run earlier than the default constructors. Must
+ * only be used for functions that have no dependency
+ * on global initialization of other QEMU subsystems.
+ */
+#define QEMU_CONSTRUCTOR_EARLY 101
+
 /*
  * Disable -ftrivial-auto-var-init on a local variable.
  *
-- 
2.50.1

Re: [PATCH v2 01/14] include: define constant for early constructor priority

Posted by Dr. David Alan Gilbert 4 weeks ago

* Daniel P. Berrangé (berrange@redhat.com) wrote:
> Functions marked with __attribute__((__constructor__)) will be
> invoked in linker order. In theory this is well defined, but
> in practice, it is hard to determine what this order will be
> with the layers of indirection through meson, ninja and the
> static libraries QEMU builds.
> 
> Notably, the order currently appears different between Linux
> and Windows (as tested with Wine on Linux). This can cause
> problems when certain QEMU constructors have a dependancy on
> other QEMU constructors.
> 
> To address this define a QEMU_CONSTRUCTOR_EARLY constant which
> provides a priority value that will run before other default
> constructors. This is to be used for QEMU constructors that
> are themselves self-contained, but may be relied upon by other
> constructors.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dave@treblig.org>

> ---
>  include/qemu/compiler.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
> index 1c2b673c05..4c49f52eb0 100644
> --- a/include/qemu/compiler.h
> +++ b/include/qemu/compiler.h
> @@ -194,6 +194,14 @@
>  # define QEMU_USED
>  #endif
>  
> +/*
> + * A priority for __attribute__((constructor(...))) that
> + * will run earlier than the default constructors. Must
> + * only be used for functions that have no dependency
> + * on global initialization of other QEMU subsystems.
> + */
> +#define QEMU_CONSTRUCTOR_EARLY 101
> +
>  /*
>   * Disable -ftrivial-auto-var-init on a local variable.
>   *
> -- 
> 2.50.1
> 
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

Re: [PATCH v2 01/14] include: define constant for early constructor priority

Posted by Richard Henderson 4 weeks ago

On 8/30/25 04:03, Daniel P. Berrangé wrote:
> Functions marked with __attribute__((__constructor__)) will be
> invoked in linker order. In theory this is well defined, but
> in practice, it is hard to determine what this order will be
> with the layers of indirection through meson, ninja and the
> static libraries QEMU builds.
> 
> Notably, the order currently appears different between Linux
> and Windows (as tested with Wine on Linux). This can cause
> problems when certain QEMU constructors have a dependancy on
> other QEMU constructors.
> 
> To address this define a QEMU_CONSTRUCTOR_EARLY constant which
> provides a priority value that will run before other default
> constructors. This is to be used for QEMU constructors that
> are themselves self-contained, but may be relied upon by other
> constructors.
> 
> Signed-off-by: Daniel P. Berrangé<berrange@redhat.com>
> ---
>   include/qemu/compiler.h | 8 ++++++++
>   1 file changed, 8 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~