34 lines
1.4 KiB
Text
34 lines
1.4 KiB
Text
/* This document is intended to provide the developer with information
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* how to integrate a new CPU (MACH) into this part of the U-Boot tree
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*/
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/** @page dev_arm_mach ARM based CPU (MACH) into the tree
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FIXME
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@par What's happens when the reset signal is gone
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@note Code running immediately after reset runs at an address it is not linked
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to: "runtime address != link address". You should only use branches and
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do not refer to fixed data. This implies the use of assembler code only.
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The ARM CPU starts at lable \<reset\> in one of the corresponding start-*.S
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files. After some basic hardware setup it can call a function
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\<arch_init_lowlevel\> if not disabled. This call is intended to give all
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developers a chance to use a standard reset vector file, but also do some
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special things required only on their specific CPU.
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After handling some MMU related things \<board_init_lowlevel\> can be called (if
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not disabled). This is a board specific function for SDRAM setup for example.
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As its board specific, your can do whatever you need to bring your board up.
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When \<board_init_lowlevel\> returns it will be assumed there is now a working
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RAM that can be used for all further steps.
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Next step is relocation of U-Boot itself. It gets copied to RAM and the last
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assembler instruction is a jump into \<start_uboot\>. This target address is
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the first C instruction in U-Boot. At this point of time:\n
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"runtime address == link address".
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*/
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