diff --git a/flash.h b/flash.h
index 4f73e0d..5d7b645 100644
--- a/flash.h
+++ b/flash.h
@@ -177,6 +177,8 @@
 /*
  * MX25 chips are SPI, first byte of device ID is memory type,
  * second byte of device ID is log(bitsize)-9.
+ * Generalplus SPI chips seem to be compatible with Macronix
+ * and use the same set of IDs.
  */
 #define MX_ID			0xC2	/* Macronix (MX) */
 #define MX_25L512		0x2010	/* 2^19 kbit or 2^16 kByte */
@@ -266,6 +268,7 @@
 #define ST_M25P10A		0x2011
 #define ST_M25P20		0x2012
 #define ST_M25P40		0x2013
+#define ST_M25P40_RES		0x12
 #define ST_M25P80		0x2014
 #define ST_M25P16		0x2015
 #define ST_M25P32		0x2016
@@ -366,7 +369,8 @@
 extern char *lb_part, *lb_vendor;
 
 /* spi.c */
-int probe_spi(struct flashchip *flash);
+int probe_spi_rdid(struct flashchip *flash);
+int probe_spi_res(struct flashchip *flash);
 int it87xx_probe_spi_flash(const char *name);
 int spi_command(unsigned int writecnt, unsigned int readcnt, const unsigned char *writearr, unsigned char *readarr);
 void spi_write_enable();
diff --git a/flashchips.c b/flashchips.c
index 123dfca..ab80bd0 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -49,26 +49,26 @@
 	{"Fujitsu",	"MBM29F400TC",		FUJITSU_ID,	MBM29F400TC_STRANGE,	512,	64 * 1024,	TEST_UNTESTED,	probe_m29f400bt,	erase_m29f400bt,		write_coreboot_m29f400bt},
 	{"Intel",	"82802AB",		INTEL_ID,	173,			512,	64 * 1024,	TEST_UNTESTED,	probe_82802ab,		erase_82802ab,			write_82802ab},
 	{"Intel",	"82802AC",		INTEL_ID,	172,			1024,	64 * 1024,	TEST_UNTESTED,	probe_82802ab,		erase_82802ab,			write_82802ab},
-	{"Macronix",	"MX25L4005",		MX_ID,		MX_25L4005,		512,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"Macronix",	"MX25L8005",		MX_ID,		MX_25L8005,		1024,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"Macronix",	"MX25L1605",		MX_ID,		MX_25L1605,		2048,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"Macronix",	"MX25L3205",		MX_ID,		MX_25L3205,		4096,	256,		TEST_OK_PREW,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"Macronix",	"MX25L4005",		MX_ID,		MX_25L4005,		512,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"Macronix",	"MX25L8005",		MX_ID,		MX_25L8005,		1024,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"Macronix",	"MX25L1605",		MX_ID,		MX_25L1605,		2048,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"Macronix",	"MX25L3205",		MX_ID,		MX_25L3205,		4096,	256,		TEST_OK_PREW,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
 	{"Macronix",	"MX29F002",		MX_ID,		MX_29F002,		256,	64 * 1024,	TEST_UNTESTED,	probe_29f002,		erase_29f002,			write_29f002},
 #ifndef DISABLE_DOC
 	{"M-Systems",	"MD-2802",		MSYSTEMS_ID,	MSYSTEMS_MD2802,	8,	8 * 1024,	TEST_UNTESTED,	probe_md2802,		erase_md2802,			write_md2802,		read_md2802},
 #endif
-	{"PMC",		"Pm25LV010",		PMC_ID,		PMC_25LV010,		128,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"PMC",		"Pm25LV016B",		PMC_ID,		PMC_25LV016B,		2048,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"PMC",		"Pm25LV020",		PMC_ID,		PMC_25LV020,		256,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"PMC",		"Pm25LV040",		PMC_ID,		PMC_25LV040,		512,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"PMC",		"Pm25LV080B",		PMC_ID,		PMC_25LV080B,		1024,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"PMC",		"Pm25LV512",		PMC_ID,		PMC_25LV512,		64,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV010",		PMC_ID,		PMC_25LV010,		128,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV016B",		PMC_ID,		PMC_25LV016B,		2048,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV020",		PMC_ID,		PMC_25LV020,		256,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV040",		PMC_ID,		PMC_25LV040,		512,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV080B",		PMC_ID,		PMC_25LV080B,		1024,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"PMC",		"Pm25LV512",		PMC_ID,		PMC_25LV512,		64,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
 	{"PMC",		"Pm49FL002",		PMC_ID_NOPREFIX,PMC_49FL002,		256,	16 * 1024,	TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_49fl004},
 	{"PMC",		"Pm49FL004",		PMC_ID_NOPREFIX,PMC_49FL004,		512,	64 * 1024,	TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_49fl004},
 	{"Sharp",	"LHF00L04",		SHARP_ID,	SHARP_LHF00L04,		1024,	64 * 1024,	TEST_UNTESTED,	probe_lhf00l04,		erase_lhf00l04,			write_lhf00l04},
-	{"Spansion",	"S25FL016A",		SPANSION_ID,	SPANSION_S25FL016A,	2048,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"SST",		"SST25VF016B",		SST_ID,		SST_25VF016B,		2048,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
-	{"SST",		"SST25VF040B",		SST_ID,		SST_25VF040B,		512,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"Spansion",	"S25FL016A",		SPANSION_ID,	SPANSION_S25FL016A,	2048,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"SST",		"SST25VF016B",		SST_ID,		SST_25VF016B,		2048,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
+	{"SST",		"SST25VF040B",		SST_ID,		SST_25VF040B,		512,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write,	spi_chip_read},
 	{"SST",		"SST28SF040A",		SST_ID,		SST_28SF040,		512,	256,		TEST_UNTESTED,	probe_28sf040,		erase_28sf040,			write_28sf040},
 	{"SST",		"SST29EE020A",		SST_ID,		SST_29EE020A,		256,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
 	{"SST",		"SST39SF010A",		SST_ID,		SST_39SF010,		128,	4096,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_39sf020},
@@ -91,15 +91,16 @@
 	{"SST",		"SST49LF040B",		SST_ID,		SST_49LF040B,		512,	64 * 1024,	TEST_UNTESTED,	probe_sst_fwhub,	erase_sst_fwhub,		write_sst_fwhub},
 	{"SST",		"SST49LF080A",		SST_ID,		SST_49LF080A,		1024,	4096,		TEST_UNTESTED,	probe_jedec,		erase_49lf040,			write_49lf040},
 	{"SST",		"SST49LF160C",		SST_ID,		SST_49LF160C,		2048,	4 * 1024,	TEST_UNTESTED,	probe_49lfxxxc,		erase_49lfxxxc,			write_49lfxxxc},
-	{"ST",		"M25P05-A",		ST_ID,		ST_M25P05A,		64,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P10-A",		ST_ID,		ST_M25P10A,		128,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P20",		ST_ID,		ST_M25P20,		256,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P40",		ST_ID,		ST_M25P40,		512,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P80",		ST_ID,		ST_M25P80,		1024,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P16",		ST_ID,		ST_M25P16,		2048,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P32",		ST_ID,		ST_M25P32,		4096,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P64",		ST_ID,		ST_M25P64,		8192,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"ST",		"M25P128",		ST_ID,		ST_M25P128,		16384,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P05-A",		ST_ID,		ST_M25P05A,		64,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P10-A",		ST_ID,		ST_M25P10A,		128,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P20",		ST_ID,		ST_M25P20,		256,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P40",		ST_ID,		ST_M25P40,		512,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P40-old",		ST_ID,		ST_M25P40_RES,		512,	256,		TEST_UNTESTED,	probe_spi_res,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P80",		ST_ID,		ST_M25P80,		1024,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P16",		ST_ID,		ST_M25P16,		2048,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P32",		ST_ID,		ST_M25P32,		4096,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P64",		ST_ID,		ST_M25P64,		8192,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"ST",		"M25P128",		ST_ID,		ST_M25P128,		16384,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
 	{"ST",		"M29F002B",		ST_ID,		ST_M29F002B,		256,	64 * 1024,	TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
 	{"ST",		"M29F002T/NT",		ST_ID,		ST_M29F002T,		256,	64 * 1024,	TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
 	{"ST",		"M29F040B",		ST_ID,		ST_M29F040B,		512,	64 * 1024,	TEST_UNTESTED,	probe_29f040b,		erase_29f040b,			write_29f040b},
@@ -118,10 +119,10 @@
 	{"SyncMOS",	"S29C51001T",		SYNCMOS_ID,	S29C51001T,		128,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_49f002},
 	{"SyncMOS",	"S29C51002T",		SYNCMOS_ID,	S29C51002T,		256,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_49f002},
 	{"SyncMOS",	"S29C51004T",		SYNCMOS_ID,	S29C51004T,		512,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_49f002},
-	{"Winbond",	"W25x10",		WINBOND_NEX_ID,	W_25X10,		128,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"Winbond",	"W25x20",		WINBOND_NEX_ID,	W_25X20,		256,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"Winbond",	"W25x40",		WINBOND_NEX_ID,	W_25X40,		512,	256,		TEST_OK_PREW,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
-	{"Winbond",	"W25x80",		WINBOND_NEX_ID,	W_25X80,		1024,	256,		TEST_UNTESTED,	probe_spi,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"Winbond",	"W25x10",		WINBOND_NEX_ID,	W_25X10,		128,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"Winbond",	"W25x20",		WINBOND_NEX_ID,	W_25X20,		256,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"Winbond",	"W25x40",		WINBOND_NEX_ID,	W_25X40,		512,	256,		TEST_OK_PREW,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
+	{"Winbond",	"W25x80",		WINBOND_NEX_ID,	W_25X80,		1024,	256,		TEST_UNTESTED,	probe_spi_rdid,		spi_chip_erase_c7,	spi_chip_write, spi_chip_read},
 	{"Winbond",	"W29C011",		WINBOND_ID,	W_29C011,		128,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
 	{"Winbond",	"W29C020C",		WINBOND_ID,	W_29C020C,		256,	128,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
 	{"Winbond",	"W29C040P",		WINBOND_ID,	W_29C040P,		512,	256,		TEST_UNTESTED,	probe_jedec,		erase_chip_jedec,		write_jedec},
@@ -136,11 +137,11 @@
 	{"Winbond",	"W39V080FA",		WINBOND_ID,	W_39V080FA,		1024,	64*1024,	TEST_UNTESTED,	probe_winbond_fwhub,	erase_winbond_fwhub,		write_winbond_fwhub},
 	{"Winbond",	"W39V080FA (dual mode)",WINBOND_ID,	W_39V080FA_DM,		512,	64*1024,	TEST_UNTESTED,	probe_winbond_fwhub,	erase_winbond_fwhub,		write_winbond_fwhub},
 
-	{"EON",		"unknown EON SPI chip",	EON_ID_NOPREFIX,GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi,		NULL,				NULL},
-	{"Macronix",	"unknown Macronix SPI chip",	MX_ID,	GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi,		NULL,				NULL},
-	{"PMC",		"unknown PMC SPI chip",	PMC_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi,		NULL,				NULL},
-	{"SST",		"unknown SST SPI chip",	SST_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi,		NULL,				NULL},
-	{"ST",		"unknown ST SPI chip",	ST_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi,		NULL,				NULL},
+	{"EON",		"unknown EON SPI chip",	EON_ID_NOPREFIX,GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi_rdid,		NULL,				NULL},
+	{"Macronix",	"unknown Macronix SPI chip",	MX_ID,	GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi_rdid,		NULL,				NULL},
+	{"PMC",		"unknown PMC SPI chip",	PMC_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi_rdid,		NULL,				NULL},
+	{"SST",		"unknown SST SPI chip",	SST_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi_rdid,		NULL,				NULL},
+	{"ST",		"unknown ST SPI chip",	ST_ID,		GENERIC_DEVICE_ID,	0,	256,		TEST_UNTESTED,	probe_spi_rdid,		NULL,				NULL},
 
 	{NULL,}
 };
diff --git a/spi.c b/spi.c
index 786d555..ddb9ff8 100644
--- a/spi.c
+++ b/spi.c
@@ -49,6 +49,16 @@
 	return 0;
 }
 
+static int spi_res(unsigned char *readarr)
+{
+	const unsigned char cmd[JEDEC_RES_OUTSIZE] = {JEDEC_RES, 0, 0, 0};
+
+	if (spi_command(JEDEC_RES_OUTSIZE, JEDEC_RES_INSIZE, cmd, readarr))
+		return 1;
+	printf_debug("RES returned %02x.\n", readarr[0]);
+	return 0;
+}
+
 void spi_write_enable()
 {
 	const unsigned char cmd[JEDEC_WREN_OUTSIZE] = {JEDEC_WREN};
@@ -65,7 +75,7 @@
 	spi_command(JEDEC_WRDI_OUTSIZE, JEDEC_WRDI_INSIZE, cmd, NULL);
 }
 
-int probe_spi(struct flashchip *flash)
+int probe_spi_rdid(struct flashchip *flash)
 {
 	unsigned char readarr[3];
 	uint32_t manuf_id;
@@ -102,6 +112,35 @@
 	return 0;
 }
 
+int probe_spi_res(struct flashchip *flash)
+{
+	unsigned char readarr[3];
+	uint32_t model_id;
+	if (!spi_rdid(readarr)) {
+		/* Check if RDID returns 0xff 0xff 0xff, then we use RES. */
+		if ((readarr[0] != 0xff) || (readarr[1] != 0xff) ||
+		    (readarr[2] != 0xff))
+			return 0;
+	} else {
+		/* We couldn't issue RDID, it's pointless to try RES. */
+		return 0;
+	}
+	if (!spi_res(readarr)) {
+		model_id = readarr[0];
+		printf_debug("%s: id 0x%x\n", __FUNCTION__, model_id);
+		if (model_id == flash->model_id) {
+			/* Print the status register to tell the
+			 * user about possible write protection.
+			 */
+			spi_prettyprint_status_register(flash);
+
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 uint8_t spi_read_status_register()
 {
 	const unsigned char cmd[JEDEC_RDSR_OUTSIZE] = {JEDEC_RDSR};
diff --git a/spi.h b/spi.h
index 15bac4e..f5c877c 100644
--- a/spi.h
+++ b/spi.h
@@ -29,6 +29,11 @@
 #define JEDEC_RDID_OUTSIZE	0x01
 #define JEDEC_RDID_INSIZE	0x03
 
+/* Read Electronic Signature */
+#define JEDEC_RES		0xab
+#define JEDEC_RES_OUTSIZE	0x04
+#define JEDEC_RES_INSIZE	0x01
+
 /* Write Enable */
 #define JEDEC_WREN		0x06
 #define JEDEC_WREN_OUTSIZE	0x01