[PATCH master v2 1/2] crc: crc-itu-t: generate lookup table on first use

[PATCH master v2 1/2] crc: crc-itu-t: generate lookup table on first use

[Ahmad Fatoum]

Unlike CRC32, CRC16 enjoys only limited use in barebox:

  - RATP
  - DDR SPD EEPROM
  - TQ EEPROM
  - SD over SPI
  - XYMODEM

Nevertheless, once one of these is enabled, a lookup table of 512 bytes
is generated, which is, by definition, badly compressible.

Let's do what CRC32 is doing and generate the lookup table anew on first
access instead.

This saves us 404 bytes for a XZ-compressed THUMB2 barebox.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 crypto/crc-itu-t.c | 69 ++++++++++++++++++++++------------------------
 include/crc.h      | 23 ----------------
 2 files changed, 33 insertions(+), 59 deletions(-)

diff --git a/crypto/crc-itu-t.c b/crypto/crc-itu-t.c
index 64bccfb7420d..837a6464b6aa 100644
--- a/crypto/crc-itu-t.c
+++ b/crypto/crc-itu-t.c
@@ -7,41 +7,36 @@
 
 #include <crc.h>
 
-/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^15 + 1) */
-const u16 crc_itu_t_table[256] = {
-	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
-	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
-	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
-	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
-	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
-	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
-	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
-	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
-	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
-	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
-	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
-	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
-	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
-	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
-	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
-	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
-	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
-	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
-	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
-	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
-	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
-	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
-	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
-	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
-	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
-	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
-	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
-	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
-	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
-	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
-	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
-	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
-};
+static u16 crc_itu_t_table[256];
+
+/*
+ * Implements the standard CRC ITU-T V.41:
+ *   Width 16
+ *   Poly  0x1021 (x^16 + x^12 + x^15 + 1)
+ *   Init  0
+ */
+static u16 crc_itu_t_byte(u16 crc, const u8 data)
+{
+	int i;
+
+	crc = crc ^ data << 8;
+	for (i = 0; i < 8; ++i) {
+		if (crc & 0x8000)
+			crc = crc << 1 ^ 0x1021;
+		else
+			crc = crc << 1;
+	}
+	return crc;
+}
+
+static void make_crc_table(void)
+{
+	if (crc_itu_t_table[1])
+		return;
+
+	for (int n = 0; n < 256; n++)
+		crc_itu_t_table[n] = crc_itu_t_byte(0, n);
+}
 
 /**
  * crc_itu_t - Compute the CRC-ITU-T for the data buffer
@@ -54,7 +49,9 @@ const u16 crc_itu_t_table[256] = {
  */
 u16 crc_itu_t(u16 crc, const u8 *buffer, size_t len)
 {
+	make_crc_table();
+
 	while (len--)
-		crc = crc_itu_t_byte(crc, *buffer++);
+		crc = (crc << 8) ^ crc_itu_t_table[((crc >> 8) ^ *buffer++) & 0xff];
 	return crc;
 }
diff --git a/include/crc.h b/include/crc.h
index a5204aaabb9c..3eba635dbaa4 100644
--- a/include/crc.h
+++ b/include/crc.h
@@ -10,31 +10,8 @@
  *   Poly  0x1021 (x^16 + x^12 + x^15 + 1)
  *   Init  0
  */
-extern u16 const crc_itu_t_table[256];
-
 extern u16 crc_itu_t(u16 crc, const u8 *buffer, size_t len);
 
-#ifdef __PBL__
-static inline u16 crc_itu_t_byte(u16 crc, const u8 data)
-{
-	int i;
-
-	crc = crc ^ data << 8;
-	for (i = 0; i < 8; ++i) {
-		if (crc & 0x8000)
-			crc = crc << 1 ^ 0x1021;
-		else
-			crc = crc << 1;
-	}
-	return crc;
-}
-#else
-static inline u16 crc_itu_t_byte(u16 crc, const u8 data)
-{
-	return (crc << 8) ^ crc_itu_t_table[((crc >> 8) ^ data) & 0xff];
-}
-#endif
-
 uint32_t crc32(uint32_t, const void *, unsigned int);
 uint32_t crc32_be(uint32_t, const void *, unsigned int);
 uint32_t crc32_no_comp(uint32_t, const void *, unsigned int);
-- 
2.39.5

[PATCH master v2 2/2] ARM: omap: add two smaller MLO defconfigs for AM335x

[Ahmad Fatoum]

The Beaglebone Black remains a popular board and it's not a good look to
have it not compile by default due to barebox getting too big.

As we keep running into size issues with the MLO defconfig, let's accept
that we die bite off more than we could chew and split off the defconfigs
into one for SD/MMC and another for NOR/NAND and document that users
should prefer those instead.

Reported-by: Sohaib Mohamed <sohaib.amhmd@gmail.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v1 -> v2:
  - add correct configs to generated_configs
---
 Documentation/boards/am335x.rst    | 28 +++++++++++++++++++++++++---
 arch/arm/Makefile                  |  6 ++++++
 common/boards/configs/nomci.config |  1 +
 common/boards/configs/nomtd.config |  1 +
 4 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 common/boards/configs/nomci.config
 create mode 100644 common/boards/configs/nomtd.config

diff --git a/Documentation/boards/am335x.rst b/Documentation/boards/am335x.rst
index f54611428bb3..ec7322a0acdf 100644
--- a/Documentation/boards/am335x.rst
+++ b/Documentation/boards/am335x.rst
@@ -8,9 +8,15 @@ loader from the same medium.
 Building barebox
 ----------------
 
-The TI AM335x boards in barebox are covered by the ``am335x_mlo_defconfig``
-for the MLO and ``omap_defconfig`` for the regular barebox image. The
-resulting images will be placed under ``images/``:
+Booting with barebox on the TI AM335x is a two-stage process and unlike
+more recently added SoCs, requires building barebox twice, each time
+with a different defconfig:
+
+* ``omap_defconfig`` for the regular (second-stage) barebox image
+* For the MLO first-stage, either ``am335x_mlo_sdmmc_defconfig`` for
+  SD/eMMC or ``am335x_mlo_rawflash_defconfig`` for raw NOR/NAND.
+
+The resulting images will be placed under ``images/``:
 
 ::
 
@@ -30,6 +36,22 @@ resulting images will be placed under ``images/``:
 
 Some boards come in different variants, make sure to pick the correct one.
 
+Size Constraints
+^^^^^^^^^^^^^^^^
+
+As the MLO needs to setup DRAM first, it must fit into the 109KiB
+of available on-Chip SRAM. Depending on the boards, drivers and general
+features enabled by your config, barebox may exceed this size resulting
+in an error message during build, e.g.::
+
+  images/start_am33xx_myirtech_sram.pblb size 111800 > maximum size 111616
+
+If you run into this issue, consider disabling some unneeded config options
+for the MLO via ``make menuconfig`` and try again.
+The ``am335x_mlo_sdmmc_defconfig`` and ``am335x_mlo_rawflash_defconfig``
+defconfigs do just that by disabling ``CONFIG_MTD`` and ``CONFIG_MCI``,
+respectively.
+
 Starting and updating barebox
 -----------------------------
 
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 6785432c52ca..270f5dfdc1c0 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -2,6 +2,12 @@
 
 KBUILD_DEFCONFIG := multi_v8_defconfig
 
+generated_configs += am335x_mlo_sdmmc_defconfig am335x_mlo_rawflash_defconfig
+am335x_mlo_sdmmc_defconfig:
+	$(call merge_into_defconfig,am335x_mlo_defconfig,nomtd)
+am335x_mlo_rawflash_defconfig:
+	$(call merge_into_defconfig,am335x_mlo_defconfig,nomci)
+
 KBUILD_CPPFLAGS	+= -D__ARM__ -fno-strict-aliasing
 # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
 ifeq ($(CONFIG_CPU_64),y)
diff --git a/common/boards/configs/nomci.config b/common/boards/configs/nomci.config
new file mode 100644
index 000000000000..f541645cccfc
--- /dev/null
+++ b/common/boards/configs/nomci.config
@@ -0,0 +1 @@
+# CONFIG_MCI is not set
diff --git a/common/boards/configs/nomtd.config b/common/boards/configs/nomtd.config
new file mode 100644
index 000000000000..f29845573ae6
--- /dev/null
+++ b/common/boards/configs/nomtd.config
@@ -0,0 +1 @@
+# CONFIG_MTD is not set
-- 
2.39.5

Re: [PATCH master v2 1/2] crc: crc-itu-t: generate lookup table on first use

[Sascha Hauer]

On Mon, 02 Dec 2024 09:08:17 +0100, Ahmad Fatoum wrote:
> Unlike CRC32, CRC16 enjoys only limited use in barebox:
> 
>   - RATP
>   - DDR SPD EEPROM
>   - TQ EEPROM
>   - SD over SPI
>   - XYMODEM
> 
> [...]

Applied, thanks!

[1/2] crc: crc-itu-t: generate lookup table on first use
      https://git.pengutronix.de/cgit/barebox/commit/?id=72f3e82057f6 (link may not be stable)
[2/2] ARM: omap: add two smaller MLO defconfigs for AM335x
      https://git.pengutronix.de/cgit/barebox/commit/?id=53c99b9f550b (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>