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Michal Privoznik
063222801a
There's a problem with glib: what we might consider functions are
in fact macros and to make things worse - they do declare local
variables. For instance here's the declaration of
g_clear_pointer() macro:
#define g_clear_pointer(pp, destroy) \
G_STMT_START \
{ \
G_STATIC_ASSERT (sizeof *(pp) == sizeof (gpointer)); \
glib_typeof ((pp)) _pp = (pp); \
glib_typeof (*(pp)) _ptr = *_pp; \
*_pp = NULL; \
if (_ptr) \
(destroy) (_ptr); \
} \
G_STMT_END \
Now, as of v6.2.0-rc1~267 our VIR_FREE() macro is in fact a
redeclaration of g_clear_pointer(). Thus, calling VIR_FREE()
increases stack size!
Ideally, this wouldn't be a problem, because those variables
(_pp, _ptr) live in their own block. And clever compiler can just
reuse space created for one block.
But then there's clang where we are hitting this exact problem in
functions like doRemoteOpen() where either g_clear_pointer() is
called directly, or there are macros like EXTRACT_URI_ARG_STR()
which hide the call away.
That's why despite our previous efforts decreasing stack size we
still needed v9.8.0-rc1~208.
Well, moving URI argument extraction (those calls to
EXTRACT_URI_ARG_* macros) into a separate function helps us
decrease stack size from 2296 bytes to 1320.
Even after this there are still more possibilities for
improvements, but those will be addressed in future commits.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Roman Bogorodskiy <bogorodskiy@gmail.com>
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==============================
Libvirt API for virtualization
==============================
Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
For some of these hypervisors, it provides a stateful management
daemon which runs on the virtualization host allowing access to the
API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other
languages including Python, Perl, PHP, Go, Java, OCaml, as well as
mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the
website:
https://libvirt.org
License
=======
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files ``COPYING.LESSER``
and ``COPYING`` for full license terms & conditions.
Installation
============
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
============
The libvirt project welcomes contributions in many ways. For most components
the best way to contribute is to send patches to the primary development
mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
=======
The libvirt project has two primary mailing lists:
* users@lists.libvirt.org (**for user discussions**)
* devel@lists.libvirt.org (**for development only**)
Further details on contacting the project are available on the website:
https://libvirt.org/contact.html