Changeset 71289 in vbox

Timestamp:

Mar 9, 2018 1:37:04 PM (7 years ago)

Author:

vboxsync

Message:

NEM: Complain about A20 too. bugref:9044

File:

trunk/src/VBox/VMM/VMMR3/NEMR3Native-win.cpp

-              r71286
+              r71289
+ *
+ *
+ * - Implementing A20 gate behavior is tedious, where as correctly emulating the
+ *   A20M# pin (present on 486 and later) is near impossible for SMP setups
+ *   (e.g. possiblity of two CPUs with different A20 status).
+ *
+ *   Workaround: Only do A20 on CPU 0, restricting the emulation to HMA.  We
+ *   unmap all pages related to HMA (0x100000..0x10ffff) when the A20 state
+ *   changes, lazily syncing the right pages back when accessed.
+ *
+ *
  * - WHVRunVirtualProcessor wastes time converting VID/Hyper-V messages to its
  *   own format (WHV_RUN_VP_EXIT_CONTEXT).

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