== Introduction == This page contains information on how to work on a bootloader replacement. == Informations == * The [http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary official u-boot source code] already has support for the S5PC110 SOC(system on a chip) that the Nexus S uses * The S5PC110 has a bootrom * The Nexus S has an usb port with an FSA9480 behind it == Links of interest == * [http://forum.xda-developers.com/showthread.php?t=1233273 Create your own I9000/S8500 (& all S5PC110 based devices) bootloader&ultimate unbrick - XDA-Developers Forums] * [http://forum.xda-developers.com/showthread.php?t=1277056 HOW-TO UnBrick the UnBrickable Vibrant - xda-developers] * [http://code.google.com/p/hummingbird-hibl/ Boot sequence interception/redirection for Hummingbird processors] * [http://code.google.com/p/hummingbird-hibl/source/browse/trunk/HummingBirdInterceptorBootloader/ source code for hummingbird-hibl] === Partitioning informations === Here's a detailed output showing the partitioning of the NAND that you can obtain with {{{ heimdall print-pit }}} with the device in download mode (VOL+ and VOL- held at reboot): {{{ Entry Count: 16 Unknown 1: 0 Unknown 2: 0 Unknown 3: 0 Unknown 4: 0 Unknown 5: 0 Unknown 6: 0 Unknown 7: 0 Unknown 8: 0 --- Entry #0 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 0 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 1 Unknown 2: 0 Unknown 3: 0 Partition Name: IPBL Filename: bootloader.img --- Entry #1 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 1 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 7 Unknown 2: 0 Unknown 3: 0 Partition Name: SBL Filename: --- Entry #2 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 2 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 7 Unknown 2: 0 Unknown 3: 0 Partition Name: SBL2 Filename: --- Entry #3 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 3 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 4 Unknown 2: 0 Unknown 3: 0 Partition Name: PARAM Filename: --- Entry #4 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 4 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 5 Unknown 2: 0 Unknown 3: 0 Partition Name: MISC Filename: --- Entry #5 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 5 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 32 Unknown 2: 0 Unknown 3: 0 Partition Name: BOOT Filename: boot.img --- Entry #6 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 6 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 32 Unknown 2: 0 Unknown 3: 0 Partition Name: RECOVERY Filename: recovery.img --- Entry #7 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 7 Partition Flags: 1 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 1878 Unknown 2: 0 Unknown 3: 0 Partition Name: CACHE Filename: cache.img --- Entry #8 --- Unused: Yes Partition Type: 0 (RFS) Partition Identifier: 8 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 54 Unknown 2: 0 Unknown 3: 0 Partition Name: RADIO Filename: radio.img --- Entry #9 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 9 Partition Flags: 1 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 27 Unknown 2: 0 Unknown 3: 0 Partition Name: EFS Filename: --- Entry #10 --- Unused: No Partition Type: 0 (RFS) Partition Identifier: 10 Partition Flags: 0 (R) Unknown 1: 0 Partition Block Size: 256 Partition Block Count: 1 Unknown 2: 0 Unknown 3: 0 Partition Name: DGS Filename: dgs.img --- Entry #11 --- Unused: No Partition Type: 2 (EXT4) Partition Identifier: 0 Partition Flags: 2 (R/W) Unknown 1: 0 Partition Block Size: 512 Partition Block Count: 2048 Unknown 2: 0 Unknown 3: 0 Partition Name: PGPT Filename: emmc.img --- Entry #12 --- Unused: No Partition Type: 2 (EXT4) Partition Identifier: 1 Partition Flags: 2 (R/W) Unknown 1: 0 Partition Block Size: 512 Partition Block Count: 1048576 Unknown 2: 0 Unknown 3: 0 Partition Name: SYSTEM Filename: system.img --- Entry #13 --- Unused: No Partition Type: 2 (EXT4) Partition Identifier: 2 Partition Flags: 2 (R/W) Unknown 1: 0 Partition Block Size: 512 Partition Block Count: 2097152 Unknown 2: 0 Unknown 3: 0 Partition Name: USERDATA Filename: userdata.img --- Entry #14 --- Unused: No Partition Type: 2 (EXT4) Partition Identifier: 3 Partition Flags: 2 (R/W) Unknown 1: 0 Partition Block Size: 512 Partition Block Count: 33554432 Unknown 2: 0 Unknown 3: 0 Partition Name: MEDIA Filename: media.img --- Entry #15 --- Unused: No Partition Type: 2 (EXT4) Partition Identifier: 4 Partition Flags: 2 (R/W) Unknown 1: 0 Partition Block Size: 512 Partition Block Count: 33 Unknown 2: 0 Unknown 3: 0 Partition Name: SGPT Filename: }}} == Serial Console == It is possible to setup a serial console on the Nexus S. It will show: * the 1st bootloader output * the 2nd bootloader output * the 2nd bootloader #2 output * the fiq debugger * (the kernel output if enabled) === How to enable serial console === * completely turn off the Nexus S * attach the microUSB connector to the Nexus S * wire GND and ID (from the microUSB connector) to a 150K resistor * get an UART to USB module like this one: http://www.dealextreme.com/p/usb-to-uart-5-pin-cp2102-module-serial-converter-81872 * wire it following this table: || UART to USB board output || resistor || microUSB connector(s) name(s) || microUSB wire color || || N/A || 150K Ohm || ID and GND || ID not wired (the 5th connector that is unused), GND is black || || 3.3V || N/A || V+ || red || || GND || N/A || GND || black || || Rx || N/A || D- || white || || Tx || N/A || D+ || green || '''Warning: the voltage to use is 3.3V and not 5V! Using 5V can cause serious damages to the UART component.''' When the USB to UART module is connected to the host PC, a new tty node will be created on the host PC, usually {{{ /dev/ttyUSB0 }}}. To read/write on the serial, you can use screen (or picocomm, or any other software that deals with serial consoles): {{{ screen /dev/ttyUSB0 115200 }}} 115200 is the baud rate to use (certainly with most UART to USB board). Then, do a regular boot. You should see the second bootloader #2 output. To get the 1st and 2nd bootloaders output, press to get in fiq debugger and write "reboot" then . Photos: here's what it looks like when all setup: [[Image(http://download.paulk.fr/replicant/crespo/uart/uart_board.jpg)]] The UART to USB board. USB is connected to the host PC, UART pins to the microUSB connector. [[Image(http://download.paulk.fr/replicant/crespo/uart/nexuss_resistor.jpg)]] The 150K resistor (two resistors here that make 150K together) soldered to the microUSB connector, that is attached to the Nexus S. ''Note: it was done the quick and dirty way here, it's better to use a protoboard (prototyping board).'' [[Image(http://download.paulk.fr/replicant/crespo/uart/nexuss_global_text.jpg)]] The USB cable that is connected to the Nexus S ends on the connectors attached to the UART to USB board. ''Note: it was done the quick and dirty way here, it's better to use a protoboard (prototyping board).'' === Bootloaders outputs === first bootloader: {{{ ----------------------------------------------------------- Samsung Primitive Bootloader (PBL) v3.0 Copyright (C) Samsung Electronics Co., Ltd. 2006-2010 ----------------------------------------------------------- Muxed OneNAND 512MB (0x50) Sync Scanning Bad Block ....... Bad Block 77 (5) Bad Block 295 (5) Bad Block 1232 (5) Bad Block 1646 (5) Bad Block 1831 (5) Bad Block 2047 (0) SBL loadding success Set cpu clk. from 400MHz to 800MHz. OM=0x9, device=OnenandMux(Audi) IROM e-fused - Secure Boot Version. }}} second bootloader: {{{ ----------------------------------------------------------- Samsung Secondary Bootloader (SBL) v3.0 Copyright (C) Samsung Electronics Co., Ltd. 2006-2010 Board Name: HERRING REV 52 Build On: Jan 20 2011 17:19:41 ----------------------------------------------------------- MMC SEM16G 15188 MB Re_partition: magic code(0x0) Muxed OneNAND 512MB (0x50) Sync Scanning Bad Block ....... Bad Block 77 (5) Bad Block 295 (5) Bad Block 1232 (5) Bad Block 1646 (5) Bad Block 1831 (5) Bad Block 2047 (0) Partitions loading success Read image(PARAM) from flash ....... Done init_fuel_gauge: vcell = 4083mV, soc = 94 PMIC_IRQ1 = 0xc0 PMIC_IRQ2 = 0x0 PMIC_IRQ3 = 0x0 PMIC_IRQ4 = 0x0 PMIC_STATUS1 = 0x0 PMIC_STATUS2 = 0x0 PMIC_STATUS3 = 0x0 PMIC_STATUS4 = 0x0 PMIC_STATUS5 = 0x0 PMIC_SMPL = 0x0 Key scan = 0x0 message.command = message.status = message.recovery = }}} second bootloader #2: {{{ BOOT_MODE_NORMAL (SW_RST(0x00000004), INFORM(0x000000ee)) LCD ID = 0x0060a953 Done Kernel(boot.img) read success from partition no.5 Setting param.serialnr = 0x3733bab6 0x6de200ec Setting param.board_rev = 0x34 Setting param.cmdline = console=ttyFIQ0 no_console_suspend androidboot.serialno=3733BAB66DE200EC androidboot.bootloader=I9020XXKA3 androidboot.baseband=I9020XXKB3 androidboot.info=0x4,0xee,1 androidboot.carrier=EUR gain_code=3 s3cfb.bootloaderfb=0x34a00000 mach-herring.lcd_type=0x00000000 oem_state=unlocked Setting param.initrd_start = 0x31000000, param.initrd_size = 0x23265 Starting kernel at 0x30008000... Uncompressing Linux... done, booting the kernel. }}} kernel {{{ }}} == TODO == * Look if [http://www.glassechidna.com.au/products/heimdall/ Heimdall] can talk to the bootrom * Serial console: * Use the correct resistors enabling the serial console on the FSA9480 * Mesure the voltage of the Nexus S serial port * Make a level shifter to shift the serial port levels * Cross compile microcom or picocom * get a serial console * Find the JTAG * look if the first stage bootloader(after the bootrom) is signed