how to tell which modules have been built into kernel?

MrUmunhum · 08-19-2009, 12:36 PM

Hi group,
I have been fighting with OpenWRT to build a kernel that will boot from a USB pen drive on my laptop. I have managed to get a bootable kernel running from a HDD. But I need to be able to use a USB flash for my RouterStation which does not have a HDD. Support from OpenWRT and Ubiquiti forums has not been overwhelming. So I turn to my favorite group of Linux minds.

How can I determine which modules have been built into my kernel?? I need to have USB support built into the kernel to be able to boot the USB file system.

MensaWater · 08-19-2009, 03:07 PM

lsmod or cat /proc/modules

w1k0 · 08-19-2009, 06:25 PM

In fact lsmod or cat /proc/modules display the information about the currently running modules only.

In the question: ``how to tell which modules have been built into kernel?'' as I understand it you ask about the features built directly into the kernel. Two above commands inform about loadable runtime modules (not built into the kernel). Features built into the kernel and stored in loadable modules are complementary. So you want the opposite information than provided by those two commands.

If the kernel was built with ``Kernel .config support'' option switched to on you can display the kernel configuration by running the command invoking extract-ikconfig script with the parameter pointing some kernel file, for example:

Code:

cd /usr/src/linux
./scripts/extract-ikconfig /boot/vmlinuz-generic-2.6.27.7

In the output you'll see the features built into kernel (y), compiled as modules (m), and not set:

Code:

#
# CPU Frequency scaling
#
CONFIG_CPU_FREQ=y
CONFIG_CPU_FREQ_TABLE=m
# CONFIG_CPU_FREQ_DEBUG is not set

These data are usually stored in provided with kernel's sources /usr/src/linux/.config file.

MensaWater · 08-20-2009, 06:58 AM

Quote:

These data are usually stored in provided with kernel's sources /usr/src/linux/.config file.

Or without the src on RedHat/CentOS/Fedora look in /boot for the config files if it isn't a kernel you compiled yourself.

The script mentioned above doesn't exist either for those Distros.

unSpawn · 08-20-2009, 07:28 AM

Running kernel support for usbfs could also be seen with 'grep usb /proc/filesystems' provided the filesystem type was used previously.