[comboot] Reset console before starting COMBOOT executable

iPXE does not call shutdown() before invoking a COMBOOT executable,
since the executable is allowed to make API calls back into iPXE.  If
a background picture is used, then the console will not be restored to
text mode before invoking the COMBOOT executable.  This can cause
undefined behaviour.

Fix by adding an explicit call to console_reset() immediately before
invoking a COMBOOT or COM32 executable, analogous to the call made to
console_reset() immediately before invokving a PXE NBP.

Debugged-by: Andrew Widdersheim <awiddersheim@inetu.net>
Tested-by: Andrew Widdersheim <awiddersheim@inetu.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/image/com32.c

@@ -40,6 +40,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/segment.h>
 #include <ipxe/init.h>
 #include <ipxe/io.h>
+#include <ipxe/console.h>
 
 /**
  * Execute COMBOOT image
@@ -281,6 +282,9 @@ static int com32_exec ( struct image *image ) {
 		return rc;
 	}
 
+	/* Reset console */
+	console_reset();
+
 	return com32_exec_loop ( image );
 }
 

src/arch/i386/image/comboot.c

@@ -40,6 +40,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/segment.h>
 #include <ipxe/init.h>
 #include <ipxe/features.h>
+#include <ipxe/console.h>
 
 FEATURE ( FEATURE_IMAGE, "COMBOOT", DHCP_EB_FEATURE_COMBOOT, 1 );
 
@@ -316,6 +317,9 @@ static int comboot_exec ( struct image *image ) {
 		return rc;
 	}
 
+	/* Reset console */
+	console_reset();
+
 	return comboot_exec_loop ( image );
 }