[Galaxy Tab 3 10.1 Android Development] Angel_666:
Santos10 Bootloader trace:

IA32 CPU Firmware
Copyright (C) 1999-2013, Intel Corporation. All rights reserved.

7[0;23r[24;75H[1K[24;1H[1mIntel(R) Atom(TM) Z2560 CPU FW 00.73 (INTELFDK)[0m8------------------------------>FOR Teewinot ONLY<-----------------------------
******************************************************************************
************** Customer release based on Rel 00.49 + TWN changes**************
**************** BZ=115220 Bypass time/date check for product ****************
****************** BZ=118523 Cold Reset on ExecuteOS failure *****************
****** BZ=124478[TW 346-500-676] Request for logging enhancement in IAFW *****
************* BZ=127192 Disable Active Refresh during JEDEC Init *************
******************* BZ=none include ucode patch M013065110E ******************
**************************** New in this code drop ***************************
***** BZ=none Changed trace to match TWN RAMDUMP application requirement *****
*************** BZ=none Removed UART and PTI HW output methods ***************
******** Short circuiting the emInit when a fixed battery is detected. *******
********************* Customization done 201308261512 MST ********************
******************************************************************************
[37;41m******************************INTEL CONFIDENTIAL******************************
[0m
0x1E, 0x20, 0x21,

ERROR:::::SPID Not Programmed, Fake data being used based on IFWI version

ERROR:::::SPID FRU Not Programmed, Fake data being used based on IFWI version

OSC_CLK3 defaults only
0x22,
OEM board; Skip spidBasedPanelNdxUpdate
0x23,
Forced Battery via SMIP FPO Bit 2
0x28, 0x2A, 0x2B, in csSFIDevsEntries, HW Id 0x0019
SFI Dev...PR3
in csSFIGpioEntries, HW Id 0x0019

SFIOEMBInit:tbl->spidTbl update
0x2C, 0x2D, 0x2F PostCodes Done

IA32 FW: CPU v000.073/00.49; SUPP v000.073/00.49; VH: 000.081/00.51
IA Timestamp: 2013.08.26:18.00 (INTELFDK)
SCU FW: ROM 177.000/B1.00; RT 033.046/21.2E
PUNIT FW: v160.064/A0.40
IFWI: v249.086/F9.56
PL: 0000010E
Config & PCB: OEM Platform, C, CLV+ B1, Samsung (01,00) SR 4Gb 1067 1GB
FHOB DW0/DW1: 00000104:00010140
I2C Expander: FFFFFFFC:0000000F
IA Options: 024020A1:00000000:03E00000:80005C00:00000101;1264
[OS HASH VERIFY] [EIST] [eMMC] [VALID BATT][WDT]

Loading OS...
pOsip = 1000000

-->OSIP verified

00000000 E0000000

[COLOR="Red"]Android COS path taken
E0000000 D303000A[/COLOR]

[COLOR="red"]Boot path override selected OS image 0[/COLOR] (OS Attribute 0x00, Reboot Reason 0x0A)
D303000A D303000A

Splash disabled in GCT

Splash display time: 2 ms
[COLOR="red"]-->Bootable OS image 0 found for requested type 2 [/COLOR](OSII attribute 0x00)
-->[COLOR="red"]Loading OS image 0 from eMMC block 0x00000032 to DRAM address 0x010FFE20[/COLOR]
-->Starting transfer of 0xA11 512-byte blocks to DRAM
-->Done loading OS Image to DRAM
-->platformConfigBuffer_pt.scuFhobDw0.osven != 0
-->osIndex: 0, Signed Image
OS image 0 PASSED verify
Booting COS

*********************************
Starting command line:
-init=/init pci=noearly console=ttyMFD2 console=ttyS0 console=logk0 earlyprintk=nologger loglevel=8 hsu_dma=7 kmemleak=off ptrace.ptrace_can_access=1 androidboot.bootmedia=sdcard androidboot.hardware=ctp_pr1 emmc_ipanic.ipanic_part_number=1 ip=50.0.0.2:50.0.0.1::255.255.255.0::usb0:on hsu_rx_wa g_android.fastboot=1 droidboot.scratch=100
-

OSNIB.wakesrc = 0x3
OSNIB.RR = 0xA

Battery is high enough for normal boot
4166mV > 0mV

Ending command line:
-init=/init pci=noearly console=ttyMFD2 console=ttyS0 console=logk0 earlyprintk=nologger loglevel=8 hsu_dma=7 kmemleak=off ptrace.ptrace_can_access=1 androidboot.bootmedia=sdcard androidboot.hardware=ctp_pr1 emmc_ipanic.ipanic_part_number=1 ip=50.0.0.2:50.0.0.1::255.255.255.0::usb0:on hsu_rx_wa g_android.fastboot=1 droidboot.scratch=100 androidboot.wakesrc=03 androidboot.mode=charger-
*********************************

WDT aka Timer7 setup
Warn Duration for Timer7: 00 seconds
Start Timer7 bit 0 -> 1: 00000000000000000000000000000000
[0;24r[24;1H[2KM
Calling OS entry point --> 0x01101000 ...

Using NEW OSHOB structure size = 176 bytes
OSNIB size = 32 bytes OEMNIB size = 64 bytes
0xFF00_0510 FullChipRegister: Status flag = 0x0
0xFF10_0510 SCFabricRegister: Status flag = 0x0
Watchdog Disabled!
usb is connected, skip to set uart path
__stmpe811_write : fail
MUIC: CONTROL1:0x00
MUIC: CONTROL1:0x00
MUIC: CONTROL2:0x3b
MUIC: CONTROL2:0x3b
[SCU_IPC_DEBUG] board ID: NOT_IDENTIFIED(8)
VERSION : 0xa501
mmc_read_ext_csd : ext_csd_rev = 0x7
cardtype: 0x00000007
SB_MMC_HS_52MHZ_1_8V_3V_IO
mmc->card_caps: 0x00000311
mmc->host_caps: 0x00000311
!!!Enter 8 Bit mode.!!!
clt_mmc_init: mmc->capacity = 0x1d56000
[BOOT] RESETIRQ1=0x00 RESETIRQ2=0x00 (interrupt tree)
[BOOT] SCU_TR=0x00020013 IA_TR=0xffffffff (oshob)
[BOOT] RR=0x00 WD=0x00 ALARM=0x00 (osnib)
[BOOT] WAKESRC=0x03 RESETIRQ1=0x20 RESETIRQ2=0x00 (osnib)

Samsung S-Boot 4.0-1816966 for GT-P5200 (Nov 26 2013 - 01:43:08)

CLT(EVT 0.0) / 1024MB / 15020MB / Rev 8 / P5200XXUAMK8

pit_check_signature (PIT) valid.
initialize_ddi_data: usable! (159:0xc)
PARAM ENV VERSION: v1.0..
pressed_key = 0x1
clt_charger_init : [battery] using external charger init(3)
STATUS1:0x3f, 2:0x43
vbvolt=0x1, chgtyp=0x3, adc=0x1f, ret=0x1031f
[check_cable_type] : Output of USB Charger Detection 3
[max77693_init_charger] : attached device(0x02) : TA
clt_max77693_set_charger_state: chg_cnfg_02 (0x1f) -> (0x1f) -> (0x1f)
clt_max77693_set_charger_state: chg_cnfg_03 (0x00) -> (0x00) -> (0x00)
clt_max77693_set_charger_state: chg_cnfg_04 (0xdd) -> (0xdd) -> (0xdd)
clt_max77693_set_charger_state: chg_cnfg_09 (0x64) -> (0x64) -> (0x64)
set_charger_state : buck(1), chg(0), reg(0x04)
init_fuel_gauge: Start!!
[0] get_adc_battid() = 92
[1] get_adc_battid() = 92
[2] get_adc_battid() = 92
get_adc_battid() = 92
init_fuel_gauge: Battery type : SDI
init_fuel_gauge: Already initialized (0x32cd, SDI type)
STATUS1:0x3f, 2:0x43
vbvolt=0x1, chgtyp=0x3, adc=0x1f, ret=0x1031f
fuel_gauge_compensate_soc: Start!!
fuel_gauge_read_soc: SOC(73), data(0x491b)
fuel_gauge_read_vcell: VCELL(4071), data(0xcb92)
calculate_table_soc: Get table SOC in case of charging!!
calculate_table_soc: i(1), vcell(4071), table_soc(88)
differ(15), table_soc(88), RepSOC(73)
clt_charger_init : cable_type(0x02)
set_charger_state : buck(1), chg(1), reg(0x05)
intel_scu_ipc_cmd_oemnib : done => 0x0
check_reboot_cmd: nCmd = 0 ... skip check_reboot_cmd
debug level = 0x4f4c
disable max77693 manual reset
clt_max77693_disable_manual_reset: set max77693 MANCTRL1 val = 0x4
clt_max77693_disable_manual_reset: read max77693 MANCTRL1 val = 0x4
disable PMIC cod off triggered by PWRBTN#: 6
do_keypad: 0x1
intel_scu_ipc_cmd_oemnib : done => 0x0
check_download: 0
Is_lpm_boot : boot-mode saved in param = 0
Is_lpm_boot : jig-on level = 0, ignore...
STATUS1:0x3f, 2:0x43
vbvolt=0x1, chgtyp=0x3, adc=0x1f, ret=0x1031f
stat=0x1031f, adc=0x1f, chg=0x3, vbvolt=1, pinLevel=1
fuel_gauge_read_vcell: VCELL(4071), data(0xcb92)
fuel_gauge_read_soc: SOC(73), data(0x491b)
check_low_battery : rb=0 jig=0
check_low_battery : v=4071 soc=73
skip check low battery
scr_draw_image: draw 'logo.jpg'...
read 'logo.jpg'(105420) completed.
<start_checksum:355>CHECKSUM_HEADER_SECTOR :4096
<start_checksum:357>offset:6144, size:6296
<start_checksum:361>CHECKSUM_HEADER_INFO : NeedChecksum:0 PartNo:27
Not Need Movinand Checksum
Movinand Checksum Confirmation Pass
load_kernel: loading boot image from 106496..
total size : 8495104
pit_check_signature (BOOT) valid.
Set valid sign flag
if_ddi_data: succeeded. (159:0xc)
BOOT_MAGIC == ANDROID!
CMDLINE LENGTH = 538
CMDLINE = init=/init console=sec_log_buf kmemleak=off ptrace.ptrace_can_access=1 androidboot.bootmedia=sdcard androidboot.hardware=santos103g sec_debug.level=0 loglevel=0 androidboot.debug_level=0x4f4c vmalloc=256m sec_log=2052K@0x10000000 sec_bootfb=0x3f000000 lcd_panel_id=0 androidboot.revision=8 switch_sel=3 cordon=615d013e557994c8ad53b3325c31b124 connie=GT-P5200_OPEN_EUR_cf878c59e3c2eeb1cdb40863938b834d androidboot.emmc_checksum=3 androidboot.bootloader=P5200XXUAMK8 androidboot.serialno=4300b61fdc125000 snd_soc_core.pmdown_time=1000 jig=0
Bootstub: map SFI MMAP to e820 table
add mmap: 0x00000000 0x00098000 1
add mmap: 0x00100000 0x00580000 2
add mmap: 0x00680000 0x00680000 1
add mmap: 0x00d00000 0x00300000 2
add mmap: 0x01000000 0x35ff0000 1
add mmap: 0x36ff0000 0x0090d000 2
add mmap: 0x378fd400 0x00100000 2
add mmap: 0x379fd400 0x02602000 1
add mmap: 0x3a000000 0x02200000 2
add mmap: 0x3c200000 0x02d00000 1
add mmap: 0x3ef00000 0x00100000 2
add mmap: 0x3f000000 0x01000000 2
add mmap: 0xfec00000 0x00001000 2
add mmap: 0xfee00000 0x00001000 2
add mmap: 0xff000000 0x01000000 2
IMR6 start=0x3a000000 end=0x3c1fffff
new mmap: 0x3a000000 0x02200000 2
IMR7 start=0x00100000 end=0x0067ffff
new mmap: 0x00100000 0x00580000 2
Final E820 table:
e820: 0x00000000 0x00098000 1
e820: 0x00100000 0x00580000 2
e820: 0x00680000 0x00680000 1
e820: 0x00d00000 0x00300000 2
e820: 0x01000000 0x35ff0000 1
e820: 0x36ff0000 0x0090d000 2
e820: 0x378fd400 0x00100000 2
e820: 0x379fd400 0x02602000 1
e820: 0x3a000000 0x02200000 2
e820: 0x3c200000 0x02d00000 1
e820: 0x3ef00000 0x00100000 2
e820: 0x3f000000 0x01000000 2
e820: 0xfec00000 0x00001000 2
e820: 0xfee00000 0x00001000 2
e820: 0xff000000 0x01000000 2
Final mb_mmap table:
mb_mmap: 0x00000000 0x00098000 1
mb_mmap: 0x00100000 0x00580000 0
mb_mmap: 0x00680000 0x00680000 1
mb_mmap: 0x00d00000 0x00300000 0
mb_mmap: 0x01000000 0x35ff0000 1
mb_mmap: 0x36ff0000 0x0090d000 0
mb_mmap: 0x378fd400 0x00100000 0
mb_mmap: 0x379fd400 0x02602000 1
mb_mmap: 0x3a000000 0x02200000 0
mb_mmap: 0x3c200000 0x02d00000 1
mb_mmap: 0x3ef00000 0x00100000 0
mb_mmap: 0x3f000000 0x01000000 0
mb_mmap: 0xfec00000 0x00001000 0
mb_mmap: 0xfee00000 0x00001000 0
mb_mmap: 0xff000000 0x01000000 0
Using bzImage to boot
Relocating initramfs to high memory ...
usb is connected, skip to set uart path
0xFF00_0510 FullChipRegister: Status flag = 0x0
0xFF10_0510 SCFabricRegister: Status flag = 0x0
Jump to kernel 32bit entry ...0x05003c00

I check interesting rows by red color. But there is easy way: need to compile x86 binaries and inject some code to twrp recovery. After that Linux OS must load from any img or partition on internal or external SD. Manual for coding this: link. This method accept to boot any second linux-based OS from any defined partition. It's on Russian - use translator to read.

Santos10 partiton table:

major minor #blocks name

7 0 61362 loop0
7 1 7308 loop1
179 0 15380480 mmcblk0
179 1 3072 mmcblk0p1
179 2 20480 mmcblk0p2
179 3 16384 mmcblk0p3
179 4 2048 mmcblk0p4
179 5 2048 mmcblk0p5
179 6 358400 mmcblk0p6
179 7 4096 mmcblk0p7
179 8 2416640 mmcblk0p8
179 9 12337152 mmcblk0p9
259 0 20480 mmcblk0p10
259 1 20480 mmcblk0p11
259 2 20480 mmcblk0p12
259 3 102400 mmcblk0p13
259 4 4096 mmcblk0p14
259 5 4096 mmcblk0p15
259 6 4096 mmcblk0p16
259 7 12288 mmcblk0p17
259 8 2048 mmcblk0p18
259 9 2048 mmcblk0p19
259 10 1024 mmcblk0p20
259 11 8192 mmcblk0p21
179 40 8192 mmcblk0gp0
179 30 1 mmcblk0rpmb
[COLOR="Red"]179 20 4096 mmcblk0boot1[/COLOR]
[COLOR="red"]179 10 4096 mmcblk0boot0[/COLOR]
252 0 307200 zram0
179 50 1955840 mmcblk1
179 51 1954816 mmcblk1p1
253 0 61362 dm-0
253 1 7308 dm-1]

Look at the red text i marked. I think we already have dual boot bootloader by Samsung.