[SeaBIOS] [PATCH 00/11] Relocate init code to high memory

Kevin O'Connor kevin at koconnor.net
Thu Sep 16 04:31:36 CEST 2010

This patch series enables SeaBIOS to relocate itself out of the
e-segment, which enables that space to be used by optionroms.

Before this patch series, SeaBIOS would typically use about half of
the e-segment.  A full debugging build could use nearly all of the
e-segment.  With this series, SeaBIOS shouldn't need anything beyond
the standard f-segment.  Future features can likely be added without
fear of limiting optionroms.

To support relocation, the build determines which parts of the 32bit
code is one-time initialization code.  It separates that out and
stores relocation information for it.  The run-time code can then copy
the initialization code to high memory and run it at that location.
The one-time init code could be called again on a soft-reboot, but
SeaBIOS now detects this case and attempts a hard-reboot.

Unfortunately, both qemu and kvm don't appear to have a reliable way
to hard-reboot - normal reboots don't reset the 0xc0000-0xfffff
memory.  I've worked around this on qemu by manually resetting that
memory.  However, kvm doesn't keep a pristine copy of the bios at
0xffff0000.  Until this is fixed, this patch series will cause a
soft-reboot on kvm to result in a shutdown instead of a reboot.

Some details on the patches: Patches 1-4 enhance the build scripts.
Patches 5-7 handle soft-reboots.  Patches 8-11 enhance the runtime to
support relocation.


Kevin O'Connor (11):
  Use str.startswith() in python scripts.
  Modify tools/layoutrom.py to use classes instead of tuples.
  Separate out init code from the rest of the 32bit flat code.
  Enhance build to emit relocation information.
  Try to hard-reboot processor on rerun of post under coreboot.
  Don't do shadow copying of optionroms when
  Try to hard-reboot on rerun of post even on emulators.
  Add memalign_tmp() helper function.
  Move init code from _start() to post().
  Move the 32bit init code to high memory at runtime.
  Enable optionroms to use freed space due to CONFIG_RELOCATE_INIT.

 Makefile            |    6 +-
 src/apm.c           |   14 +-
 src/config.h        |    2 +
 src/ioport.h        |    1 +
 src/optionroms.c    |   18 ++-
 src/pci.c           |   10 +
 src/pci.h           |    1 +
 src/pmm.c           |    8 -
 src/post.c          |  164 +++++++++++++++---
 src/ps2port.c       |   16 ++-
 src/ps2port.h       |    3 +-
 src/shadow.c        |   40 +++--
 src/stacks.c        |    4 +-
 src/types.h         |   10 +-
 src/util.h          |   13 ++-
 tools/checkrom.py   |    9 +-
 tools/checkstack.py |   14 +-
 tools/layoutrom.py  |  465 ++++++++++++++++++++++++++++++++-------------------
 18 files changed, 535 insertions(+), 263 deletions(-)


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