This is far too small for a valid command line. Here is a typical example of how long that line should be on a TX2 (this is all a single line even though the forum might line wrap):
root=/dev/mmcblk0p1 rw rootwait console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 video=tegrafb no_console_suspend=1 earlycon=uart8250,mmio32,0x3100000 nvdumper_reserved=0x2772e0000 gpt usbcore.old_scheme_first=1 tegraid=18.1.2.0.0 maxcpus=6 boot.slot_suffix= boot.ratchetvalues=0.2031647.1 bl_prof_dataptr=0x10000@0x275840000 sdhci_tegra.en_boot_part_access=1 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4
Somewhere the “console=tty0,quiet” replaced the entire command line, rather than appending to it. Also, if there is a space between “tty0,” and “quiet”, then this is an error. Individual arguments to different drivers are separated via a space as a delimiter. When multiple arguments are given to an individual driver, then a comma separates those arguments (without spaces). This means the “console=tty,” is in error, and still needs an argument after the comma, without using spaces. Going directly from a comma to a space should never occur.
If you examine a command line in the older extlinux.conf when this was not seeded with the device tree “chosen->bootargs” entry, there would be one very long line to do so, without any newline/linefeed. Example from my earlier example, had it been purely through extlinux.conf:
APPEND root=/dev/mmcblk0p1 rw rootwait console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 video=tegrafb no_console_suspend=1 earlycon=uart8250,mmio32,0x3100000 nvdumper_reserved=0x2772e0000 gpt usbcore.old_scheme_first=1 tegraid=18.1.2.0.0 maxcpus=6 boot.slot_suffix= boot.ratchetvalues=0.2031647.1 bl_prof_dataptr=0x10000@0x275840000 sdhci_tegra.en_boot_part_access=1 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4
Notice in that example the key word “APPEND”. The extra content was intended to go on the end, and not replace previous content. So for example, if my “chosen->bootargs” entry in device tree were this:
root=/dev/mmcblk0p1 rw rootwait console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 video=tegrafb no_console_suspend=1 earlycon=uart8250,mmio32,0x3100000 nvdumper_reserved=0x2772e0000 gpt usbcore.old_scheme_first=1 tegraid=18.1.2.0.0 maxcpus=6 boot.slot_suffix= boot.ratchetvalues=0.2031647.1 bl_prof_dataptr=0x10000@0x275840000 sdhci_tegra.en_boot_part_access=1 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4
…then my “APPEND”, to add “quiet”, would simply be:
APPEND quiet
…which would have resulted in “cat /proc/cmdline” showing (differing only by a space and the word “quiet” at the end):
root=/dev/mmcblk0p1 rw rootwait console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 video=tegrafb no_console_suspend=1 earlycon=uart8250,mmio32,0x3100000 nvdumper_reserved=0x2772e0000 gpt usbcore.old_scheme_first=1 tegraid=18.1.2.0.0 maxcpus=6 boot.slot_suffix= boot.ratchetvalues=0.2031647.1 bl_prof_dataptr=0x10000@0x275840000 sdhci_tegra.en_boot_part_access=1 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 quiet
…note the space and the word “quiet” appended to the end of the content that was in the device tree.
Basically, your kernel, even if perfectly valid, has no chance to boot because it has a very messed up command line. To be clear, some content should exist based on the device tree’s “chosen->bootargs” node. Content from the extlinux.conf’s “APPEND” key/value pair would append to the end of this. Arguments from “APPEND” would all be on a single line, and a space is used between individual driver command lines. Commas are used for multiple arguments within a single driver, and no comma should ever have a space directly after it.
Perhaps the device tree “chosen->bootargs” never loaded. Perhaps confusion with the comma followed by a space broke something. Perhaps an incorrect signature caused the device tree “chosen->bootargs” to be rejected. Perhaps a modified kernel did not have the right configuration to load “chosen->bootargs”. I do not know, but it will be mandatory to fix this before you continue.