From: Oliver Kurth <okurth@vmware.com>
Date: Sun, 21 Jul 2019 00:15:19 +0000 (-0700)
Subject: Common header file change not applicable to open-vm-tools.
X-Git-Tag: stable-11.1.0~316
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e26fc358cba5a594927c7dcf7c2e06307374ffc8;p=thirdparty%2Fopen-vm-tools.git

Common header file change not applicable to open-vm-tools.
---

diff --git a/open-vm-tools/lib/include/backdoor_def.h b/open-vm-tools/lib/include/backdoor_def.h
index e65b5c679..64b4a4b54 100644
--- a/open-vm-tools/lib/include/backdoor_def.h
+++ b/open-vm-tools/lib/include/backdoor_def.h
@@ -481,10 +481,13 @@ Backdoor_CmdRequiresValidSegments(unsigned cmd)
  * This is the mechanism to favor from EL0 because it has a negligible impact
  * on vCPU performance.
  *
- * o From EL1 and EL0
+ * o From EL1 and EL0, only when monitor_control.hv_hypercall = "TRUE"
  * The vCPU executes the BRK (64-bit code) or BKPT (32-bit code) instruction
  * with the immediate X86_IO_MAGIC. Note that T32 code requires an 8-bit
  * immediate.
+ * Pro: This mechanism cannot be intercepted by EL3 code.
+ * Con: This mechanism has a significant impact on vCPU performance when
+ *      running a debugger in the guest.
  *
  * 4) Read from general-purpose registers specific to the x86 I/O space
  *    instruction.