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Diffstat (limited to 'en/boot-installer/arm.xml')
| -rw-r--r-- | en/boot-installer/arm.xml | 118 |
1 files changed, 114 insertions, 4 deletions
diff --git a/en/boot-installer/arm.xml b/en/boot-installer/arm.xml index c3c367442..c3999173e 100644 --- a/en/boot-installer/arm.xml +++ b/en/boot-installer/arm.xml @@ -1,13 +1,123 @@ <!-- retain these comments for translator revision tracking --> <!-- $Id$ --> - <sect2 arch="arm" id="boot-tftp"><title>Booting from TFTP</title> - -&boot-installer-intro-net.xml; - + <sect2 arch="arm" id="boot-image-formats"> + <title>Boot image formats</title> + <para> + On ARM-based systems in most cases one of two formats for boot images + is used: a) standard Linux zImage-format kernels + (<quote>vmlinuz</quote>) in conjunction with standard Linux initial + ramdisks (<quote>initrd.gz</quote>) or b) uImage-format kernels + (<quote>uImage</quote>) in conjunction with corresponding initial + ramdisks (<quote>uInitrd</quote>). + </para> + <para> + uImage/uInitrd are image formats designed for the u-boot firmware that + is used on many ARM-based systems. Older u-boot versions can only + boot files in uImage/uInitrd format, so these are often used on + older armel systems. Newer u-boot versions can - besides booting + uImages/uInitrds - also boot standard Linux kernels and ramdisk images, + but the command syntax to do that is slightly different from that + for booting uImages. + </para> + <para> + For systems using a multiplatform kernel, besides kernel and initial + ramdisk a so-called device-tree file (or device-tree blob, + <quote>dtb</quote>) is needed. It is specific to each supported system + and contains a description of the particular hardware. + </para> </sect2> + <sect2 arch="arm" id="boot-tftp"><title>Booting by TFTP</title> +&boot-installer-intro-net.xml; + + <sect3 arch="arm" id="boot-tftp-uboot"> + <title>TFTP-booting in u-boot</title> + <para> + Network booting on systems using the u-boot firmware consists of + three steps: a) configuring the network, b) loading the images + (kernel/initial ramdisk/dtb) into memory and c) actually executing + the previosly loaded code. + </para> + <para> + First you have to configure the network, either automatically via + DHCP by running +<informalexample><screen> +setenv autoload no +dhcp +</screen></informalexample> + or manually by setting several environment variables +<informalexample><screen> +setenv ipaddr <ip address of the client> +setenv netmask <netmask> +setenv serverip <ip address of the tftp server> +setenv dnsip <ip address of the nameserver> +setenv gatewayip <ip address of the default gateway> +</screen></informalexample> + If you prefer, you can make these settings permanent by running +<informalexample><screen> +saveenv +</screen></informalexample> + </para> + <para> + Afterwards you need to load the the images (kernel/initial + ramdisk/dtb) into memory. This is done with the tftpboot command, + which has to be provided with the address at which the image + shall be stored in memory. Unfortunately the memory map can vary + from system to system, so there is no general rule which addresses + can be used for this. + </para> + <para> + On some systems, u-boot predefines a set of environment variables + with suitable load addresses: kernel_addr_r, ramdisk_addr_r and + fdt_addr_r. You can check whether they are defined by running +<informalexample><screen> +printenv kernel_addr_r ramdisk_addr_r fdt_addr_r +</screen></informalexample> + If they are not defined, you have to check your system's + documentation for appropriate values and set them manually. For + systems based on Allwinner SunXi SOCs (e.g. the Allwinner A10, + architecture name <quote>sun4i</quote> or the Allwinner A20, + architecture name <quote>sun7i</quote>), you can e.g. use the + follwing values: +<informalexample><screen> +setenv kernel_addr_r 0x46000000 +setenv fdt_addr_r 0x47000000 +setenv ramdisk_addr_r 0x48000000 +</screen></informalexample> + </para> + <para> + When the load addresses are defined, you can load the images + into memory from the previously defined tftp server with +<informalexample><screen> +tftpboot ${kernel_addr_r} <filename of the kernel image> +tftpboot ${fdt_addr_r} <filename of the dtb> +tftpboot ${ramdisk_addr_r} <filename of the initial ramdisk image> +</screen></informalexample> + </para> + <para> + The third part is actually executing the loaded code, for which the + exact command depends on the image format used. With uImage/uInitrd, + the command is +<informalexample><screen> +bootm ${kernel_addr_r} ${ramdisk_addr_r} ${fdt_addr_r} +</screen></informalexample> + and with native Linux images it is +<informalexample><screen> +bootz ${kernel_addr_r} ${ramdisk_addr_r}:${filesize} ${fdt_addr_r} +</screen></informalexample> + </para> + <para> + Note: When booting standard linux images, it is important to load + the initial ramdisk image after the kernel and the dtb as u-boot + sets the filesize variable to the size of the last file loaded and + the bootz command requires the size of the ramdisk image to work + correctly. In case of booting a platform-specific kernel, i.e. a + kernel without device-tree, simply omit the ${fdt_addr_r} parameter. + </para> + </sect3> + </sect2> <sect2 arch="arm"><title>Booting from CD-ROM</title> &boot-installer-intro-cd.xml; |