Hi. I'm tinkering with uboot sources right now
For a Kobo Aura HD
giorgio130 guesses are OK and safe to implement on kobos with internal SD card.
But flashing new bootloaders don't change the boot process cause u-boot uses his own environment in mmc.
The only way I found to stop the autoboot is deleting the kernel. This way I get a prompt but only for a few seconds, because the watchdog.
I can also change bootdelay on uboot but not too much because wdog
Bootlog of an OEM SDcard
Code:
U-Boot 2009.08-dirty-svn ( 3月 01 2013 - 11:22:42)
CPU: Freescale i.MX50 family 1.1V at 800 MHz
mx50 pll1: 800MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Board: MX50 RDP board
Boot Reason: [POR]
Boot Device: SD
I2C: ready
DRAM: 512 MB
MMC: FSL_ESDHC: 0, FSL_ESDHC: 1, FSL_ESDHC: 2
In: serial
Out: serial
Err: serial
[_get_sd_number] g_sd_number:2
MMC read: dev # 2, block # 1023, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 2, block # 1024, count 1 partition # 0 ...
1 blocks read: OK
ram p=70000000,size=536870912
MMC read: dev # 2, block # 18431, count 1 partition # 0 ...
1 blocks read: OK
no "logo" bin header
MMC read: dev # 2, block # 14335, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 2, block # 14336, count 2263 partition # 0 ...
2263 blocks read: OK
Kernel RAM visiable size=510M->510M
init TPS65185 power ...
Relock PLL1 to 1GHz ...
mx50 pll1: 1000MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Hit any key to stop autoboot: 0
MMC read: dev # 2, block # 2047, count 1 partition # 0 ...
1 blocks read: OK
no kernel image signature !
MMC read: dev # 2, block # 2048, count 8192 partition # 0 ...
8192 blocks read: OK
## Booting kernel from Legacy Image at 70800000 ...
Image Name: r6512_#1040 Mar 10 12:00:37
Created: 2015-03-10 4:00:39 UTC
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1891780 Bytes = 1.8 MB
Load Address: 70008000
Entry Point: 70008000
Loading Kernel Image ... OK
OK
Starting kernel ...
Bootlog of an OEM SDcard with custom uboot:
Code:
U-Boot 2009.08 (jun 11 2016 - 13:33:02)
CPU: Freescale i.MX50 family 1.1V at 800 MHz
mx50 pll1: 800MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Board: MX50 RDP board
Boot Reason: [POR]
Boot Device: SD
I2C: ready
DRAM: 512 MB
MMC: FSL_ESDHC: 0, FSL_ESDHC: 1, FSL_ESDHC: 2
In: serial
Out: serial
Err: serial
[_get_sd_number] g_sd_number:2
MMC read: dev # 2, block # 1023, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 2, block # 1024, count 1 partition # 0 ...
1 blocks read: OK
ram p=70000000,size=536870912
MMC read: dev # 2, block # 18431, count 1 partition # 0 ...
1 blocks read: OK
no "logo" bin header
MMC read: dev # 2, block # 14335, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 2, block # 14336, count 2263 partition # 0 ...
2263 blocks read: OK
Kernel RAM visiable size=510M->510M
init TPS65185 power ...
Relock PLL1 to 1GHz ...
mx50 pll1: 1000MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Hit any key to stop autoboot: 0
MMC read: dev # 2, block # 2047, count 1 partition # 0 ...
1 blocks read: OK
no kernel image signature !
MMC read: dev # 2, block # 2048, count 8192 partition # 0 ...
8192 blocks read: OK
## Booting kernel from Legacy Image at 70800000 ...
Image Name: r6512_#1040 Mar 10 12:00:37
Created: 2015-03-10 4:00:39 UTC
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1891780 Bytes = 1.8 MB
Load Address: 70008000
Entry Point: 70008000
Loading Kernel Image ... OK
OK
Starting kernel ...
Bootlog of an almost-empty SDcard (first 512K copied)
Code:
U-Boot 2009.08-dirty-svn ( 3月 01 2013 - 11:22:42)
CPU: Freescale i.MX50 family 1.1V at 800 MHz
mx50 pll1: 800MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Board: MX50 RDP board
Boot Reason: [POR]
Boot Device: SD
I2C: ready
DRAM: 512 MB
MMC: FSL_ESDHC: 0, FSL_ESDHC: 1, FSL_ESDHC: 2
In: serial
Out: serial
Err: serial
[_get_sd_number] g_sd_number:2
MMC read: dev # 2, block # 1023, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 2, block # 1024, count 1 partition # 0 ...
1 blocks read: OK
ram p=70000000,size=536870912
MMC read: dev # 2, block # 18431, count 1 partition # 0 ...
1 blocks read: OK
no "logo" bin header
MMC read: dev # 2, block # 14335, count 1 partition # 0 ...
1 blocks read: OK
no "waveform" bin header
Kernel RAM visiable size=511M->511M
Hit any key to stop autoboot: 0
MMC read: dev # 2, block # 2047, count 1 partition # 0 ...
1 blocks read: OK
no kernel image signature !
MMC read: dev # 2, block # 2048, count 8192 partition # 0 ...
8192 blocks read: OK
Wrong Image Format for bootm command
ERROR: can't get kernel image!