20-24 September 2021
US/Pacific timezone

Bootconfig and kernel cmdline

24 Sep 2021, 08:00
45m
Refereed Track/Virtual-Room (LPC Virtual)

Refereed Track/Virtual-Room

LPC Virtual

150
LPC Refereed Track (Closed) LPC Refereed Track

Speaker

Masami Hiramatsu (Linaro Ltd.)

Description

In the recent kernel, Extra Boot Configuration (bootconfig) is available to pass the kernel boot parameters in the structured key-data form instead of single-line command line. The parameters passed via bootconfig are just merged to the kernel command line string(cmdline). Thus the kernel modules/subsystems can continue using kernel cmdline APIs, but can not use the bootconfig APIs for the parameters given by cmdline.
The bootconfig API obviously gives a different programming model for the parameter parsing for kernel modules. The kernel module_params API is passive, main use case is callbacks handles a fixed parameter. On the other hand, the bootconfig API is active, user modules queries the parameters from the bootconfig in their preferred order and the parameter name can be dynamically expanding. If both APIs are available in the kernel modules/subsystems, users can specify more complex configuration not just setting parameter values.
This session will explain what is the bootconfig and the relationship of the cmdline, and discuss what will be the issue to unify cmdline and bootconfig in API level.

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Primary author

Masami Hiramatsu (Linaro Ltd.)

Presentation Materials