== 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

=== 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: 
}}}

== 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