[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

@@ -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
 #

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 $@
 

src/arch/i386/prefix/hromprefix.S

@@ -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"

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: