Changeset 46234 in vbox for trunk/src/VBox/Devices/PC/BIOS

Timestamp:

May 23, 2013 1:21:37 PM (12 years ago)

Author:

vboxsync

Message:

BIOS: updated notes.

File:

• trunk/src/VBox/Devices/PC/BIOS/notes.txt (modified) (2 diffs)

trunk/src/VBox/Devices/PC/BIOS/notes.txt

@@ -59 +59 @@
   newer systems prefer ACPI.
 
+- QNX4 calls 16-bit protected-mode PCI BIOS in an environment where ESP is
+  16-bit but SS is a 32-bit stack segment. In such environments, using the
+  ENTER/LEAVE sequence is fatal if the high word of EBP is non-zero (which
+  it will be with QNX 4.25). LEAVE propagates the high word of EBP into ESP
+  with fatal consequences.
+
+- Plan 9 also runs 16-bit code with a 32-bit stack segment, except Plan 9
+  thinks it counts as real mode. Same ENTER/LEAVE problem as above.
+
 
  Notes on BIOS implementation
@@ -98 +107 @@
   with a small 32->16 thunk.
 
+- The -of switch can be used to avoid generating ENTER/LEAVE instructions.
+  This appears to be an undocumented and perhaps unintentional side effect.
+
 
  Code size notes (code as of 7/6/2011):