Replicant

== 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