linuxboot: fix loading old kernels

Old kernels that used high memory only allowed the initrd to be in the
first 896MB of memory.  If you load the initrd above, they complain
that "initrd extends beyond end of memory".

In order to fix this, while not breaking machines with small amounts
of memory fixed by cdebec5 (linuxboot: compute initrd loading address,
2014-10-06), we need to distinguish two cases.  If pc.c placed the
initrd at end of memory, use the new algorithm based on the e801
memory map.  If instead pc.c placed the initrd at the maximum address
specified by the bzImage, leave it there.

The only interesting part is that the low-memory info block is now
loaded very early, in real mode, and thus the 32-bit address has
to be converted into a real mode segment.  The initrd address is
also patched in the info block before entering real mode, it is
simpler that way.

This fixes booting the RHEL4.8 32-bit installation image with 1GB
of RAM.

Cc: qemu-stable@nongnu.org
Cc: mst@redhat.com
Cc: jsnow@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 files changed
tree: 3b04d961c85678cc0f5afa45fb6bca7c3aa9a74b
  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. libcacard/
  14. libdecnumber/
  15. linux-headers/
  16. linux-user/
  17. net/
  18. pc-bios/
  19. po/
  20. qapi/
  21. qga/
  22. qobject/
  23. qom/
  24. roms/
  25. scripts/
  26. slirp/
  27. stubs/
  28. sysconfigs/
  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-tricore/
  44. target-unicore32/
  45. target-xtensa/
  46. tcg/
  47. tests/
  48. trace/
  49. ui/
  50. util/
  51. .exrc
  52. .gitignore
  53. .gitmodules
  54. .mailmap
  55. .travis.yml
  56. accel.c
  57. aio-posix.c
  58. aio-win32.c
  59. arch_init.c
  60. async.c
  61. balloon.c
  62. block-migration.c
  63. block.c
  64. blockdev-nbd.c
  65. blockdev.c
  66. blockjob.c
  67. bootdevice.c
  68. bt-host.c
  69. bt-vhci.c
  70. Changelog
  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.c
  87. exec.c
  88. gdbstub.c
  89. HACKING
  90. hmp-commands.hx
  91. hmp.c
  92. hmp.h
  93. iohandler.c
  94. ioport.c
  95. iothread.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.c
  106. migration-exec.c
  107. migration-fd.c
  108. migration-rdma.c
  109. migration-tcp.c
  110. migration-unix.c
  111. migration.c
  112. module-common.c
  113. monitor.c
  114. nbd.c
  115. numa.c
  116. os-posix.c
  117. os-win32.c
  118. page_cache.c
  119. qapi-schema.json
  120. qdev-monitor.c
  121. qdict-test-data.txt
  122. qemu-bridge-helper.c
  123. qemu-char.c
  124. qemu-coroutine-io.c
  125. qemu-coroutine-lock.c
  126. qemu-coroutine-sleep.c
  127. qemu-coroutine.c
  128. qemu-doc.texi
  129. qemu-file-stdio.c
  130. qemu-file-unix.c
  131. qemu-file.c
  132. qemu-img-cmds.hx
  133. qemu-img.c
  134. qemu-img.texi
  135. qemu-io-cmds.c
  136. qemu-io.c
  137. qemu-log.c
  138. qemu-nbd.c
  139. qemu-nbd.texi
  140. qemu-options-wrapper.h
  141. qemu-options.h
  142. qemu-options.hx
  143. qemu-seccomp.c
  144. qemu-tech.texi
  145. qemu-timer.c
  146. qemu.nsi
  147. qemu.sasl
  148. qmp-commands.hx
  149. qmp.c
  150. qtest.c
  151. README
  152. rules.mak
  153. savevm.c
  154. softmmu_template.h
  155. spice-qemu-char.c
  156. tcg-runtime.c
  157. tci.c
  158. thread-pool.c
  159. thunk.c
  160. tpm.c
  161. trace-events
  162. translate-all.c
  163. translate-all.h
  164. user-exec.c
  165. VERSION
  166. version.rc
  167. vl.c
  168. vmstate.c
  169. xbzrle.c
  170. xen-common-stub.c
  171. xen-common.c
  172. xen-hvm-stub.c
  173. xen-hvm.c
  174. xen-mapcache.c