Limit for the kernel command line in a boot configuration
The CONFIG_COMMAND_LINE_SIZE option in the kernel configuration menu specifies the maximum number of characters that boot configurations can hold for the kernel command line.
The value is an integer in the range 896 to 1048576. 896 corresponds to the former fixed value of 895 characters plus a terminator byte. 1048576 characters is equivalent to 1 MB. The default length is 4096 characters, which is the maximum that can be passed to the kernel, including parameters that are specified when booting.
Kernel builders: This information is intended for those who want to
build their own kernel. Be aware that both compiling your own kernel or recompiling an existing
distribution usually means that you have to maintain your kernel yourself.
Figure 1 shows where to find CONFIG_COMMAND_LINE_SIZE in the configuration menu.
Processor type and features ---> ... Maximum size of kernel command line (CONFIG_COMMAND_LINE_SIZE)