diff options
| author | Michael Brown | 2015-06-23 21:37:55 +0200 |
|---|---|---|
| committer | Michael Brown | 2015-06-23 21:51:19 +0200 |
| commit | e46154fbb4cbbf8ec5d93b0d81915b220fd4c7a3 (patch) | |
| tree | f03ca73408e1ae3cc98101c6ca98edff698598c6 /src/include/ipxe/bitmap.h | |
| parent | [xhci] Ignore invalid protocol speed ID values on Intel Skylake platforms (diff) | |
| download | ipxe-e46154fbb4cbbf8ec5d93b0d81915b220fd4c7a3.tar.gz ipxe-e46154fbb4cbbf8ec5d93b0d81915b220fd4c7a3.tar.xz ipxe-e46154fbb4cbbf8ec5d93b0d81915b220fd4c7a3.zip | |
[pci] Use flat real mode to call INT 1a,b101
Some HP BIOSes (observed with an HP ProLiant m710p Server Cartridge)
have a bug in the implementation of INT 1a,b101: they blithely assume
that real-mode code is able to read from anywhere in the 32-bit memory
space.
This problem affects the call to INT 1a,b101 made from within
pcibios_num_bus() (which uses REAL_CODE() and hence executes in
genuine real mode) but does not affect the call made from within
romprefix.S (since with a PMM BIOS, that call executes in flat real
mode anyway).
Work around the problem by explicitly calling flatten_real_mode()
before invoking INT 1a,b101. This is a rarely-used code path, and so
the extra overhead of emulating instructions in some VM configurations
(see commit 6d4deee ("[librm] Use genuine real mode to accelerate
operation in virtual machines") for more details) is negligible.
Reported-by: Wissam Shoukair <wissams@mellanox.com>
Debugged-by: Wissam Shoukair <wissams@mellanox.com>
Debugged-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/include/ipxe/bitmap.h')
0 files changed, 0 insertions, 0 deletions