From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Edwards Date: Mon, 23 Apr 2012 16:24:20 +0000 (UTC) Subject: [Buildroot] [OT] How to get rootfs.cpio combined with a kernel? Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net I've been trying to figure out how to combined the rootfs.cpio created by Buildroot with an externally built kernel, and I'm a little stumped. The "standard" way to do it is to set CONFIG_INITRAMFS_SOURCE to point to the cpio archive and have the kernel build pull in the rootfs cpio archive when the kernel is built. That works, but not a very good solution when it comes to configuration management for a shipping project. I need to be able to build and manage/version the kernel and rootfs as separate objects -- then combine the kernel and rootfs together into a single uImage file. IOW, I'd like to do two _separate_ builds: 1) Build rootfs.cpio (using Buildroot). 2) Build vmlinux.o (not sure if that's the right file). Those would both be controlled and versioned as separate objects. Then I'd like to link those two files together and create a uImage file from them. I've been browsing around Linux kernel Makefiles and docs, trying to figure out what the "pre-rootfs" file is and how to combine it with the rootfs to produce the uImage file. There's plenty of info about how to specify or create an initramfs and the actual kernel startup works, but all I can find about how to actually link the kernel and initramfs together is "set CONFIG_INITRAMFS_SOURCE and do a kernel build". Having to re-compile the kernel when nothing in the kernel or it's configuration has changed (only the rootfs changed) just doesn't feel like an acceptable engineering practice. Any pointers to documentation on how one might combine a kernel object and a rootfs cpio image to get a uImage file? -- Grant Edwards grant.b.edwards Yow! ANN JILLIAN'S HAIR at makes LONI ANDERSON'S gmail.com HAIR look like RICARDO MONTALBAN'S HAIR!