[pcbios] Add facility for testing arbitrary E820 memory maps

We seem to be having issues with various E820 memory maps.  These
problems are often difficult to reproduce, requiring access to the
specific system exhibiting the problem.

Add a facility for hooking in a fake E820 map generator, using an
arbitrary map defined in a C array, solely in order to be able to test
the map-mangling code against arbitrary E820 maps.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/arch/i386/firmware/pcbios/hidemem.c b/src/arch/i386/firmware/pcbios/hidemem.c
index 202081b6..c9df7bd0 100644
--- a/src/arch/i386/firmware/pcbios/hidemem.c
+++ b/src/arch/i386/firmware/pcbios/hidemem.c
@@ -19,10 +19,14 @@
 #include <realmode.h>
 #include <biosint.h>
 #include <basemem.h>
+#include <fakee820.h>
 #include <gpxe/init.h>
 #include <gpxe/memmap.h>
 #include <gpxe/hidemem.h>
 
+/** Set to true if you want to test a fake E820 map */
+#define FAKE_E820 0
+
 /** Alignment for hidden memory regions */
 #define ALIGN_HIDDEN 4096   /* 4kB page alignment should be enough */
 
@@ -135,6 +139,13 @@ static void hide_etherboot ( void ) {
 	DBG ( "Hiding gPXE from system memory map\n" );
 	get_memmap ( &memmap );
 
+	/* Hook in fake E820 map, if we're testing one */
+	if ( FAKE_E820 ) {
+		DBG ( "Hooking in fake E820 map\n" );
+		fake_e820();
+		get_memmap ( &memmap );
+	}
+
 	/* Initialise the hidden regions */
 	hide_basemem();
 	hide_umalloc ( virt_to_phys ( _text ), virt_to_phys ( _text ) );
@@ -194,6 +205,10 @@ static void unhide_etherboot ( int flags __unused ) {
 	 */
 	unhook_bios_interrupt ( 0x15, ( unsigned int ) int15,
 				&int15_vector );
+
+	/* Unhook fake E820 map, if used */
+	if ( FAKE_E820 )
+		unfake_e820();
 }
 
 /** Hide Etherboot startup function */