--- /dev/null
+++ /sys/src/cmd/aux/aout2efi.c	Thu Sep  3 00:00:00 2026
@@ -0,0 +1,237 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <mach.h>
+
+#define	HDRSZ	0x200	/* EFI header size */
+
+enum {
+	EFI_IMAGE_MACHINE_IA32		= 0x014c,
+	EFI_IMAGE_MACHINE_x64		= 0x8664,
+	EFI_IMAGE_MACHINE_AARCH64	= 0xAA64,
+};
+
+static int	is32;
+static int	infd, outfd;
+static uchar	buf[IOUNIT];
+
+static void
+pack(uchar **pp, char *fmt, ...)
+{
+	va_list args;
+	int c;
+	uchar *p;
+	u32int u;
+	u64int l;
+
+	va_start(args, fmt);
+	for(; *fmt; fmt++){
+		c = *fmt;
+		if(c == 'q' && is32)
+			c = 'l';
+		p = *pp;
+		switch(c){
+		case 'b':
+			p[0] = va_arg(args, int);
+			*pp += 1;
+			break;
+		case 'w':
+			u = va_arg(args, u32int);
+			p[0] = u;
+			p[1] = u>>8;
+			*pp += 2;
+			break;
+		case 'l':
+			u = va_arg(args, u32int);
+			p[0] = u;
+			p[1] = u>>8;
+			p[2] = u>>16;
+			p[3] = u>>24;
+			*pp += 4;
+			break;
+		case 'q':
+			l = va_arg(args, u64int);
+			p[0] = l;
+			p[1] = l>>8;
+			p[2] = l>>16;
+			p[3] = l>>24;
+			p[4] = l>>32;
+			p[5] = l>>40;
+			p[6] = l>>48;
+			p[7] = l>>56;
+			*pp += 8;
+			break;
+		case '0':
+			*pp += va_arg(args, int);
+			break;
+		default:
+			sysfatal("pack: %c", c);
+		}
+	}
+	va_end(args);
+}
+
+static void
+usage(void)
+{
+	fprint(2, "usage: %s a.out\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char **argv)
+{
+	Fhdr fhdr;
+	u64int kzero;
+	uchar *header;
+	char *ofile, *iname;
+	int arch, chars, relocs;
+	long n, szofdat, szofimage;
+
+	kzero = 0x8000;
+	ofile = nil;
+	relocs = 0;
+	ARGBEGIN{
+	case 'Z':
+		kzero = strtoull(EARGF(usage()), 0, 0);
+		break;
+	case 'o':
+		ofile = strdup(EARGF(usage()));
+		break;
+	default:
+		usage();
+	}ARGEND;
+
+	if(argc != 1)
+		usage();
+
+	infd = open(argv[0], OREAD);
+	if(infd < 0)
+		sysfatal("infd: %r");
+
+	if(crackhdr(infd, &fhdr) == 0)
+		sysfatal("crackhdr: %r");
+	switch(mach->mtype){
+	case MI386:
+		arch = EFI_IMAGE_MACHINE_IA32;
+		is32 = 1;
+		chars = 2103;
+		break;
+	case MAMD64:
+		arch = EFI_IMAGE_MACHINE_x64;
+		chars = 2223;
+		break;
+	case MARM64:
+		arch = EFI_IMAGE_MACHINE_AARCH64;
+		chars = 518;
+		relocs = 1;
+		break;
+	default:
+		sysfatal("archloch");
+	}
+	szofdat = fhdr.txtsz + fhdr.datsz;
+	szofimage = szofdat + fhdr.bsssz + HDRSZ;
+
+	iname = strrchr(argv[0], '/');
+	if(iname != nil)
+		iname++;
+	else
+		iname = argv[0];
+	if(ofile == nil)
+		ofile = smprint("%s.efi", iname);
+	outfd = create(ofile, OWRITE|OTRUNC, 0666);
+	if(outfd < 0)
+		sysfatal("create: %r");
+
+	header = buf;
+
+	/* mzhdr */
+	pack(&header, "bb0l",
+		'M', 'Z',	/* e_magic */
+		0x3a,		/* UNUSED */
+		0x40);		/* e_lfanew */
+
+	/* pehdr */
+	pack(&header, "bbbbwwlllww",
+		'P', 'E', 0, 0,
+		arch,			/* Machine */
+		1+relocs,		/* NumberOfSections */
+		0,			/* TimeDateStamp UNUSED */
+		0,			/* PointerToSymbolTable UNUSED */
+		0,			/* NumberOfSymbols UNUSED */
+		is32 ? 0xE0 : 0xF0,	/* SizeOfOptionalHeader */
+		chars);			/* Characteristics */
+	pack(&header, "wbblllll",
+		is32 ? 0x10B : 0x20B,	/* Magic */
+    		9,			/* MajorLinkerVersion UNUSED */
+		0,			/* MinorLinkerVersion UNUSED */
+		0,			/* SizeOfCode UNUSED */
+		0,			/* SizeOfInitializedData UNUSED */
+		0,			/* SizeOfUninitializedData UNUSED */
+		fhdr.entry-kzero,	/* AddressOfEntryPoint */
+		0);			/* BaseOfCode UNUSED */
+	if(is32)
+	pack(&header, "l", 0);	/* BaseOfData UNUSED */
+	pack(&header, "qllwwwwwwllllwwqqqqll0",
+		kzero,		/* ImageBase */
+		HDRSZ,		/* SectionAlignment */
+		HDRSZ,		/* FileAlignment */
+		4,		/* MajorOperatingSystemVersion UNUSED */
+		0,		/* MinorOperatingSystemVersion UNUSED */
+		0,		/* MajorImageVersion UNUSED */
+		0,		/* MinorImageVersion UNUSED */
+		4,		/* MajorSubsystemVersion */
+		0,		/* MinorSubsystemVersion UNUSED */
+		0,		/* Win32VersionValue UNUSED */
+		szofimage,	/* SizeOfImage */
+ 		HDRSZ,		/* SizeOfHeaders */
+ 		0,		/* CheckSum UNUSED */
+		10,		/* Subsystem (10 = efi application) */
+		0,		/* DllCharacteristics UNUSED */
+		0,		/* SizeOfStackReserve UNUSED */
+		0,		/* SizeOfStackCommit UNUSED */
+		0,		/* SizeOfHeapReserve UNUSED */
+		0,		/* SizeOfHeapCommit UNUSED */
+		0,		/* LoaderFlags UNUSED */
+		16,		/* NumberOfRvaAndSizes UNUSED */
+		32*4);		/* RVA UNUSED */
+	if(relocs)
+	pack(&header, "bbbbbbbbllllllwwl",
+		'.', 'r', 'e', 'l', 'o', 'c', 0, 0,
+		0,		/* VirtualSize */
+		0,		/* VirtualAddress */
+		0,		/* SizeOfData */
+		0,		/* PointerToRawData */
+		0,		/* PointerToRelocations UNUSED */
+		0,		/* PointerToLinenumbers UNUSED */
+		0,		/* NumberOfRelocations UNUSED */
+		0,		/* NumberOfLinenumbers UNUSED */
+		0x42100040);	/* Characteristics (read, discardable) */
+	pack(&header, "bbbbbbbbllllllwwl",
+		'.', 't', 'e', 'x', 't', 0, 0, 0,
+		szofdat,	/* VirtualSize */
+		HDRSZ,		/* VirtualAddress */
+		szofdat,	/* SizeOfData */
+		HDRSZ,		/* PointerToRawData */
+		0,		/* PointerToRelocations UNUSED */
+		0,		/* PointerToLinenumbers UNUSED */
+		0,		/* NumberOfRelocations UNUSED */
+		0,		/* NumberOfLinenumbers UNUSED */
+		0x86000020);	/* Characteristics (code, RWX) */
+
+	if(write(outfd, buf, HDRSZ) != HDRSZ)
+		sysfatal("write: %r");
+	if(seek(infd, fhdr.hdrsz, 0) != fhdr.hdrsz)
+		sysfatal("seek: %r");
+	for(;;){
+		n = read(infd, buf, sizeof(buf));
+		if(n < 0)
+			sysfatal("read: %r");
+		if(n == 0)
+			break;
+		if(write(outfd, buf, n) != n)
+			sysfatal("write: %r");
+	}
+
+	exits(nil);
+}
--- /n/sources/plan9/sys/src/cmd/aux/mkfile	Thu Aug 16 22:50:45 2012
+++ /sys/src/cmd/aux/mkfile	Thu Sep  3 00:00:00 2026
@@ -5,6 +5,7 @@
 	9pcon\
 	accupoint\
 	acidleak\
+	aout2efi\
 	apm\
 	astarld\
 	cddb\