Which file in the /proc filesystem lists parameters passed from the bootloader to the kernel?

The file in the /proc filesystem that lists parameters passed from the bootloader to the kernel is cmdline. This file contains the complete command line that was used to boot the kernel, including all kernel parameters that were specified in the bootloader configuration.

When the system boots, the bootloader (such as GRUB) passes arguments to the kernel, and these arguments can influence the kernel's behavior during startup. The cmdline file provides a convenient way to access this information after the system has booted, allowing users and administrators to review how the kernel was initialized.

The other options do not specifically represent files that are part of the /proc filesystem that would provide this information. For instance, while bootparams and kernelargs may seem relevant, they are not standard or recognized files in the /proc filesystem for capturing boot parameters in modern Linux distributions. The config file typically refers to kernel configuration options rather than the boot parameters themselves. Thus, cmdline is the definitive source for this information within the /proc filesystem architecture.