From f04cf9239addd12d6be9e7ff137262755e3680d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Fri, 9 Oct 2015 17:17:19 +0200 Subject: util: add linux-only memfd fallback MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement memfd_create() fallback if not available in system libc. memfd_create() is still not included in glibc today, atlhough it's been available since Linux 3.17 in Oct 2014. memfd has numerous advantages over traditional shm/mmap for ipc memory sharing with fd handler, which we are going to make use of for vhost-user logging memory in following patches. The next patches are going to introduce helpers to use best practices of memfd usage and provide some compatibility fallback. memfd.c is thus temporarily useless and eventually empty if memfd_create() is provided by the system. Signed-off-by: Marc-André Lureau Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Tested-by: Thibaut Collet --- include/qemu/memfd.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 include/qemu/memfd.h (limited to 'include') diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h new file mode 100644 index 0000000000..8b1fe6ad66 --- /dev/null +++ b/include/qemu/memfd.h @@ -0,0 +1,20 @@ +#ifndef QEMU_MEMFD_H +#define QEMU_MEMFD_H + +#include "config-host.h" + +#ifndef F_LINUX_SPECIFIC_BASE +#define F_LINUX_SPECIFIC_BASE 1024 +#endif + +#ifndef F_ADD_SEALS +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9) +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10) + +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */ +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ +#define F_SEAL_GROW 0x0004 /* prevent file from growing */ +#define F_SEAL_WRITE 0x0008 /* prevent writes */ +#endif + +#endif /* QEMU_MEMFD_H */ -- cgit v1.2.3