configure: Don't fall back to gthread coroutine backend

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 simplify
the Makefile logic so it just links in the backend the configure
script selects.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1365419487-19867-3-git-send-email-peter.maydell@linaro.org
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
3 files changed
tree: 9f02cbdcac4c105dd98b4e92164e65b05a990239
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. default-configs/
  6. disas/
  7. docs/
  8. fpu/
  9. fsdev/
  10. gdb-xml/
  11. hw/
  12. include/
  13. ldscripts/
  14. libcacard/
  15. linux-headers/
  16. linux-user/
  17. net/
  18. pc-bios/
  19. po/
  20. qapi/
  21. qga/
  22. QMP/
  23. qobject/
  24. qom/
  25. roms/
  26. scripts/
  27. slirp/
  28. stubs/
  29. sysconfigs/
  30. target-alpha/
  31. target-arm/
  32. target-cris/
  33. target-i386/
  34. target-lm32/
  35. target-m68k/
  36. target-microblaze/
  37. target-mips/
  38. target-moxie/
  39. target-openrisc/
  40. target-ppc/
  41. target-s390x/
  42. target-sh4/
  43. target-sparc/
  44. target-unicore32/
  45. target-xtensa/
  46. tcg/
  47. tests/
  48. tpm/
  49. trace/
  50. ui/
  51. util/
  52. .exrc
  53. .gitignore
  54. .gitmodules
  55. .mailmap
  56. aio-posix.c
  57. aio-win32.c
  58. arch_init.c
  59. async.c
  60. balloon.c
  61. block-migration.c
  62. block.c
  63. blockdev-nbd.c
  64. blockdev.c
  65. blockjob.c
  66. bt-host.c
  67. bt-vhci.c
  68. Changelog
  69. cmd.c
  70. cmd.h
  71. CODING_STYLE
  72. configure
  73. COPYING
  74. COPYING.LIB
  75. coroutine-gthread.c
  76. coroutine-sigaltstack.c
  77. coroutine-ucontext.c
  78. coroutine-win32.c
  79. cpu-exec.c
  80. cpus.c
  81. cputlb.c
  82. device-hotplug.c
  83. device_tree.c
  84. disas.c
  85. dma-helpers.c
  86. dump-stub.c
  87. dump.c
  88. exec.c
  89. gdbstub.c
  90. HACKING
  91. hmp-commands.hx
  92. hmp.c
  93. hmp.h
  94. iohandler.c
  95. ioport.c
  96. kvm-all.c
  97. kvm-stub.c
  98. LICENSE
  99. main-loop.c
  100. MAINTAINERS
  101. Makefile
  102. Makefile.objs
  103. Makefile.target
  104. memory.c
  105. memory_mapping-stub.c
  106. memory_mapping.c
  107. migration-exec.c
  108. migration-fd.c
  109. migration-tcp.c
  110. migration-unix.c
  111. migration.c
  112. monitor.c
  113. nbd.c
  114. os-posix.c
  115. os-win32.c
  116. page_cache.c
  117. qapi-schema-test.json
  118. qapi-schema.json
  119. qdev-monitor.c
  120. qdict-test-data.txt
  121. qemu-bridge-helper.c
  122. qemu-char.c
  123. qemu-coroutine-io.c
  124. qemu-coroutine-lock.c
  125. qemu-coroutine-sleep.c
  126. qemu-coroutine.c
  127. qemu-doc.texi
  128. qemu-img-cmds.hx
  129. qemu-img.c
  130. qemu-img.texi
  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.sasl
  142. qmp-commands.hx
  143. qmp.c
  144. qtest.c
  145. readline.c
  146. README
  147. rules.mak
  148. savevm.c
  149. spice-qemu-char.c
  150. tcg-runtime.c
  151. tci.c
  152. thread-pool.c
  153. thunk.c
  154. trace-events
  155. translate-all.c
  156. translate-all.h
  157. user-exec.c
  158. VERSION
  159. version.rc
  160. vl.c
  161. xbzrle.c
  162. xen-all.c
  163. xen-mapcache.c
  164. xen-stub.c