On Mon, 2008-08-11 at 09:12 -0700, Tim Bird wrote: > Fundu wrote: > > Hi, > > First off i have a ppc based board. > > and i'm trying to load a kernel image with ramdisk rootfs. > > > > i have build the kernel. it spit uImage,zImage and vmlinux.gz > > > > my question are. > > 1) what are all the different image types ? > > i know the uImage is just the kernel, what are the rest (zImage & vmlinux.gz)? > > vmlinux is the uncompressed result of compiling and linking the kernel. > > I presume that vmlinux.gz is a gzipped version of vmlinux. > > zImage is some other compressed kernel image format. zImage (for ppc at least), is a "wrapper" around the kernel that does the load and decompress. It's akin to how uImage works, just for non-U-Boot platforms. > uImage is another kernel image format, with information > specifically for loading with U-Boot. > > You can see what commands are being used to create these different > images by using "V=1" with your kernel make. (e.g. make V=1 uImage) > > On my machine, I see the following: > /bin/sh /a/home/tbird/work/tiny/branch_ss/scripts/mkuboot.sh -A arm -O linux -T kernel -C none -a 0x10008000 -e 0x10008000 -n 'Linux-2.6.23.17-alp_nl-gfcc28266' -d arch/arm/boot/zImage > arch/arm/boot/uImage > > If I recall correctly, mkuboot.sh prepends the > size and start location for the kernel onto the zImage, in order to create > the uImage. However, don't take my word for it -- see the U-Boot > documentation, or even better read the mkuboot.sh source, or the source > for U-Boot itself. That's the beauty of open source. You can see all > the software and examine/modify any part you want. mkuboot.sh is a script that calls the 'mkimage' tool that is provided with the U-Boot source code. I'd also recommend reading the U-Boot source code to better understand this if your board uses U-Boot as the bootloader. > > If the source is impenetrable, there's always the U-Boot mailing list. > > > 2) i'm using u-boot as the bootldr. so i download the uImage (cause > > zImage and vmlinux.gz aren't bootlable) from tftp server and then do > > bootm <address> the kernel only load partially. How does the kernel > > know where/how to load the rootfs ? > > Usually, you tell it with a command line option (root=...). > The command line can come from the boot loader, or it may be compiled > into the kernel binary. See Documentation/kernel-parameters.txt > for information about kernel command line options. And for U-Boot, you want to make sure the command line is set via the 'bootargs' U-Boot environment variable. josh -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
