util: add linux-only memfd fallback

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 <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
3 files changed
tree: 2e4b4d17ddc7e9f3ee839f8a78dc56a2949d5f6d
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. crypto/
  6. default-configs/
  7. disas/
  8. docs/
  9. fpu/
  10. fsdev/
  11. gdb-xml/
  12. hw/
  13. include/
  14. libdecnumber/
  15. linux-headers/
  16. linux-user/
  17. migration/
  18. net/
  19. pc-bios/
  20. po/
  21. qapi/
  22. qga/
  23. qobject/
  24. qom/
  25. roms/
  26. scripts/
  27. slirp/
  28. stubs/
  29. target-alpha/
  30. target-arm/
  31. target-cris/
  32. target-i386/
  33. target-lm32/
  34. target-m68k/
  35. target-microblaze/
  36. target-mips/
  37. target-moxie/
  38. target-openrisc/
  39. target-ppc/
  40. target-s390x/
  41. target-sh4/
  42. target-sparc/
  43. target-tilegx/
  44. target-tricore/
  45. target-unicore32/
  46. target-xtensa/
  47. tcg/
  48. tests/
  49. trace/
  50. ui/
  51. util/
  52. .dir-locals.el
  53. .exrc
  54. .gitignore
  55. .gitmodules
  56. .mailmap
  57. .travis.yml
  58. accel.c
  59. aio-posix.c
  60. aio-win32.c
  61. arch_init.c
  62. async.c
  63. balloon.c
  64. block.c
  65. blockdev-nbd.c
  66. blockdev.c
  67. blockjob.c
  68. bootdevice.c
  69. bt-host.c
  70. bt-vhci.c
  71. Changelog
  72. CODING_STYLE
  73. configure
  74. COPYING
  75. COPYING.LIB
  76. coroutine-gthread.c
  77. coroutine-sigaltstack.c
  78. coroutine-ucontext.c
  79. coroutine-win32.c
  80. cpu-exec-common.c
  81. cpu-exec.c
  82. cpus.c
  83. cputlb.c
  84. device-hotplug.c
  85. device_tree.c
  86. disas.c
  87. dma-helpers.c
  88. dump.c
  89. exec.c
  90. gdbstub.c
  91. HACKING
  92. hmp-commands-info.hx
  93. hmp-commands.hx
  94. hmp.c
  95. hmp.h
  96. iohandler.c
  97. ioport.c
  98. iothread.c
  99. kvm-all.c
  100. kvm-stub.c
  101. LICENSE
  102. main-loop.c
  103. MAINTAINERS
  104. Makefile
  105. Makefile.objs
  106. Makefile.target
  107. memory.c
  108. memory_mapping.c
  109. module-common.c
  110. monitor.c
  111. nbd.c
  112. numa.c
  113. os-posix.c
  114. os-win32.c
  115. page_cache.c
  116. qapi-schema.json
  117. qdev-monitor.c
  118. qdict-test-data.txt
  119. qemu-bridge-helper.c
  120. qemu-char.c
  121. qemu-coroutine-io.c
  122. qemu-coroutine-lock.c
  123. qemu-coroutine-sleep.c
  124. qemu-coroutine.c
  125. qemu-doc.texi
  126. qemu-ga.texi
  127. qemu-img-cmds.hx
  128. qemu-img.c
  129. qemu-img.texi
  130. qemu-io-cmds.c
  131. qemu-io.c
  132. qemu-log.c
  133. qemu-nbd.c
  134. qemu-nbd.texi
  135. qemu-options-wrapper.h
  136. qemu-options.h
  137. qemu-options.hx
  138. qemu-seccomp.c
  139. qemu-tech.texi
  140. qemu-timer.c
  141. qemu.nsi
  142. qemu.sasl
  143. qjson.c
  144. qmp-commands.hx
  145. qmp.c
  146. qtest.c
  147. README
  148. rules.mak
  149. softmmu_template.h
  150. spice-qemu-char.c
  151. tcg-runtime.c
  152. tci.c
  153. thread-pool.c
  154. thunk.c
  155. tpm.c
  156. trace-events
  157. translate-all.c
  158. translate-all.h
  159. translate-common.c
  160. user-exec.c
  161. VERSION
  162. version.rc
  163. vl.c
  164. xen-common-stub.c
  165. xen-common.c
  166. xen-hvm-stub.c
  167. xen-hvm.c
  168. xen-mapcache.c