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Diffstat (limited to 'doc/usage/environment.rst')
| -rw-r--r-- | doc/usage/environment.rst | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/doc/usage/environment.rst b/doc/usage/environment.rst index 28a8952..83543f6 100644 --- a/doc/usage/environment.rst +++ b/doc/usage/environment.rst @@ -204,7 +204,9 @@ fdt_high to work it must reside in writable memory, have sufficient padding on the end of it for u-boot to add the information it needs into it, and the memory - must be accessible by the kernel. + must be accessible by the kernel. This usage is strongly discouraged + however as it also stops U-Boot from ensuring the device tree starting + address is properly aligned and a misaligned tree will cause OS failures. fdtcontroladdr if set this is the address of the control flattened @@ -240,14 +242,21 @@ initrd_high memory. In this case U-Boot will NOT COPY the ramdisk at all. This may be useful to reduce the boot time on your system, but requires that this - feature is supported by your Linux kernel. + feature is supported by your Linux kernel. This usage however requires + that the user ensure that there will be no overlap with other parts of the + image such as the Linux kernel BSS. It should not be enabled by default + and only done as part of optimizing a deployment. ipaddr IP address; needed for tftpboot command loadaddr Default load address for commands like "bootp", - "rarpboot", "tftpboot", "loadb" or "diskboot" + "rarpboot", "tftpboot", "loadb" or "diskboot". Note that the optimal + default values here will vary between architectures. On 32bit ARM for + example, some offset from start of memory is used as the Linux kernel + zImage has a self decompressor and it's best if we stay out of where that + will be working. loads_echo see CONFIG_LOADS_ECHO @@ -390,7 +399,6 @@ in U-Boot code. ================= ============== ================ ============== Image File Name RAM Address Flash Location ================= ============== ================ ============== -u-boot u-boot u-boot_addr_r u-boot_addr Linux kernel bootfile kernel_addr_r kernel_addr device tree blob fdtfile fdt_addr_r fdt_addr ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr |