From 8ffea19225a450f2bde34510d9c2c913ac0c0021 Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Mon, 19 Apr 2010 20:38:35 +0100
Subject: [PATCH] [romprefix] Remove .hrom prefix

The .hrom prefix provides an experimental mechanism for reducing
option ROM space usage on systems where PMM allocation fails, by
pretending that PMM allocation succeeded and gave us an address fixed
at compilation time.  This is unreliable, and potentially dangerous.
In particular, when multiple gPXE ROMs are present in a system, each
gPXE ROM will assume ownership of the same fixed address, resulting in
undefined behaviour.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/Makefile.housekeeping         |  1 -
 src/arch/i386/Makefile.pcbios     |  2 --
 src/arch/i386/prefix/hromprefix.S | 12 ------------
 src/arch/i386/prefix/romprefix.S  | 13 -------------
 4 files changed, 28 deletions(-)
 delete mode 100644 src/arch/i386/prefix/hromprefix.S

diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index efd85ea3..a7162e6f 100644
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -866,7 +866,6 @@ endif # defined(BIN)
 #
 FINALISE_rom	= $(MAKEROM) $(MAKEROM_FLAGS) $(TGT_MAKEROM_FLAGS) \
 		  -i$(IDENT) -s 0 $@
-FINALISE_hrom	= $(FINALISE_rom)
 
 # Some ROMs require specific flags to be passed to makerom.pl
 #
diff --git a/src/arch/i386/Makefile.pcbios b/src/arch/i386/Makefile.pcbios
index dcabbdf7..e3c33872 100644
--- a/src/arch/i386/Makefile.pcbios
+++ b/src/arch/i386/Makefile.pcbios
@@ -11,7 +11,6 @@ LDFLAGS		+= -N --no-check-sections
 # Media types.
 #
 MEDIA		+= rom
-MEDIA		+= hrom
 MEDIA		+= pxe
 MEDIA		+= kpxe
 MEDIA		+= kkpxe
@@ -24,7 +23,6 @@ MEDIA		+= raw
 # Padding rules
 #
 PAD_rom		= $(PADIMG) --blksize=512 --byte=0xff $@
-PAD_hrom	= $(PAD_rom)
 PAD_dsk		= $(PADIMG) --blksize=512 $@
 PAD_hd		= $(PADIMG) --blksize=32768 $@
 
diff --git a/src/arch/i386/prefix/hromprefix.S b/src/arch/i386/prefix/hromprefix.S
deleted file mode 100644
index 03acf1e2..00000000
--- a/src/arch/i386/prefix/hromprefix.S
+++ /dev/null
@@ -1,12 +0,0 @@
-/*****************************************************************************
- * ROM prefix that relocates to HIGHMEM_LOADPOINT during POST if PMM allocation
- * fails. Intended to be used, with caution, on BIOSes that support PCI3.00 but
- * have limited PMM support, such as most AMI BIOSes.
- *****************************************************************************
- */
-
-FILE_LICENCE ( GPL2_OR_LATER )
-
-#define SHRINK_WITHOUT_PMM
-
-#include "romprefix.S"
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S
index e7d146eb..2d70cd21 100644
--- a/src/arch/i386/prefix/romprefix.S
+++ b/src/arch/i386/prefix/romprefix.S
@@ -352,7 +352,6 @@ got_pmm: /* PMM allocation succeeded */
 	call	print_character
 	movw	%si, %ax
 	call	print_hex_byte
-pmm_copy:
 	/* Copy ROM to PMM block */
 	xorw	%ax, %ax
 	movw	%ax, %es
@@ -364,19 +363,7 @@ pmm_copy:
 	movl	%edi, decompress_to
 	/* Shrink ROM */
 	movb	$_prefix_memsz_sect, romheader_size
-#ifdef SHRINK_WITHOUT_PMM
-	jmp	pmm_done
 pmm_fail:
-	/* Print marker and copy ourselves to high memory */
-	movl	$HIGHMEM_LOADPOINT, image_source
-	xorw	%di, %di
-	movb	$( '!' ), %al
-	call	print_character
-	jmp	pmm_copy
-pmm_done:
-#else
-pmm_fail:
-#endif
 	/* Restore upper register halves */
 	popal
 no_pmm: