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Commit | Line | Data |
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f1d2b313 HS |
1 | To make relocation on arm working, the following changes are done: |
2 | ||
92d5ecba | 3 | At arch level: add linker flag -pie |
f1d2b313 | 4 | |
92d5ecba AA |
5 | This causes the linker to generate fixup tables .rel.dyn and .dynsym, |
6 | which must be applied to the relocated image before transferring | |
7 | control to it. | |
f1d2b313 | 8 | |
92d5ecba AA |
9 | These fixups are described in the ARM ELF documentation as type 23 |
10 | (program-base-relative) and 2 (symbol-relative) | |
f1d2b313 | 11 | |
92d5ecba | 12 | At cpu level: modify linker file and add a relocation and fixup loop |
f1d2b313 | 13 | |
92d5ecba AA |
14 | the linker file must be modified to include the .rel.dyn and .dynsym |
15 | tables in the binary image, and to provide symbols for the relocation | |
16 | code to access these tables | |
f1d2b313 | 17 | |
92d5ecba AA |
18 | The relocation and fixup loop must be executed after executing |
19 | board_init_f at initial location and before executing board_init_r | |
20 | at final location. | |
f1d2b313 | 21 | |
92d5ecba | 22 | At board level: |
f1d2b313 | 23 | |
92d5ecba AA |
24 | dram_init(): bd pointer is now at this point not accessible, so only |
25 | detect the real dramsize, and store it in gd->ram_size. Bst detected | |
26 | with get_ram_size(). | |
f1d2b313 | 27 | |
92d5ecba | 28 | TODO: move also dram initialization there on boards where it is possible. |
f1d2b313 | 29 | |
92d5ecba AA |
30 | Setup of the the bd_t dram bank info is done in the new function |
31 | dram_init_banksize() called after bd is accessible. | |
f1d2b313 | 32 | |
92d5ecba | 33 | At lib level: |
f1d2b313 | 34 | |
92d5ecba | 35 | Board.c code is adapted from ppc code |
f1d2b313 | 36 | |
92d5ecba | 37 | At config level: |
f1d2b313 | 38 | |
92d5ecba | 39 | Undefine CONFIG_SYS_ARM_WITHOUT_RELOC |
f1d2b313 | 40 | |
92d5ecba AA |
41 | * WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING * |
42 | ||
43 | Boards which are not fixed to support relocation will be REMOVED! | |
44 | ||
2e5167cc WD |
45 | Eventually, CONFIG_SYS_ARM_WITHOUT_RELOC will disappear and boards |
46 | which have to migrated to relocation will disappear too. | |
f1d2b313 | 47 | |
92d5ecba AA |
48 | ----------------------------------------------------------------------------- |
49 | ||
50 | For boards which boot from nand_spl, it is possible to save one copy | |
14d0a02a | 51 | if CONFIG_SYS_TEXT_BASE == relocation address! This prevents that uboot code |
ab86f72c HS |
52 | is copied again in relocate_code(). |
53 | ||
54 | example for the tx25 board: | |
55 | ||
56 | a) cpu starts | |
57 | b) it copies the first page in nand to internal ram | |
58 | (nand_spl_code) | |
59 | c) end executes this code | |
60 | d) this initialize CPU, RAM, ... and copy itself to RAM | |
61 | (this bin must fit in one page, so board_init_f() | |
62 | don;t fit in it ... ) | |
63 | e) there it copy u-boot to CONFIG_SYS_NAND_U_BOOT_DST and | |
64 | starts this image @ CONFIG_SYS_NAND_U_BOOT_START | |
65 | f) u-boot code steps through board_init_f() and calculates | |
66 | the relocation address and copy itself to it | |
67 | ||
14d0a02a | 68 | If CONFIG_SYS_TEXT_BASE == relocation address, the copying of u-boot |
ab86f72c HS |
69 | in f) could be saved. |
70 | ||
92d5ecba | 71 | ----------------------------------------------------------------------------- |
ab86f72c | 72 | |
92d5ecba | 73 | TODO |
f1d2b313 HS |
74 | |
75 | - fill in bd_t infos (check) | |
76 | - adapt all boards | |
77 | ||
14d0a02a | 78 | - maybe adapt CONFIG_SYS_TEXT_BASE (this must be checked from board maintainers) |
f1d2b313 HS |
79 | This *must* be done for boards, which boot from NOR flash |
80 | ||
14d0a02a | 81 | on other boards if CONFIG_SYS_TEXT_BASE = relocation baseaddr, this saves |
f1d2b313 HS |
82 | one copying from u-boot code. |
83 | ||
84 | - new function dram_init_banksize() is actual board specific. Maybe | |
85 | we make a weak default function in arch/arm/lib/board.c ? | |
86 | ||
92d5ecba | 87 | ----------------------------------------------------------------------------- |
f1d2b313 HS |
88 | |
89 | Relocation with NAND_SPL (example for the tx25): | |
90 | ||
91 | - cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE) | |
92 | and start with code execution on this address. | |
93 | ||
94 | - The First page contains u-boot code from u-boot:nand_spl/nand_boot_fsl_nfc.c | |
071bc923 | 95 | which inits the dram, cpu registers, reloacte itself to CONFIG_SYS_TEXT_BASE and loads |
f1d2b313 HS |
96 | the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution |
97 | @CONFIG_SYS_NAND_U_BOOT_START | |
98 | ||
c8d76eaf WD |
99 | - This u-boot does no RAM init, nor CPU register setup. Just look |
100 | where it has to copy and relocate itself to this address. If | |
101 | relocate address = CONFIG_SYS_TEXT_BASE (not the same, as the | |
102 | CONFIG_SYS_TEXT_BASE from the nand_spl code), then there is no need | |
103 | to copy, just go on with bss clear and jump to board_init_r. | |
f1d2b313 | 104 | |
92d5ecba | 105 | ----------------------------------------------------------------------------- |
f1d2b313 | 106 | |
92d5ecba | 107 | How ELF relocations 23 and 2 work. |
f1d2b313 | 108 | |
92d5ecba | 109 | TBC |
f1d2b313 HS |
110 | |
111 | ------------------------------------------------------------------------------------- | |
112 | ||
113 | Debugging u-boot in RAM: | |
114 | (example on the qong board) | |
115 | ||
116 | a) add in config.mk: | |
117 | ||
118 | PLATFORM_CPPFLAGS += -DDEBUG | |
119 | ||
120 | ----------------- | |
121 | ||
122 | b) start debugger | |
123 | ||
124 | arm-linux-gdb u-boot | |
125 | ||
126 | [hs@pollux u-boot]$ arm-linux-gdb u-boot | |
127 | GNU gdb Red Hat Linux (6.7-2rh) | |
128 | Copyright (C) 2007 Free Software Foundation, Inc. | |
129 | License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> | |
130 | This is free software: you are free to change and redistribute it. | |
131 | There is NO WARRANTY, to the extent permitted by law. Type "show copying" | |
132 | and "show warranty" for details. | |
133 | This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-linux". | |
134 | The target architecture is set automatically (currently arm) | |
135 | .. | |
136 | (gdb) | |
137 | ||
138 | ----------------- | |
139 | ||
140 | c) connect to target | |
141 | ||
142 | target remote bdi10:2001 | |
143 | ||
144 | (gdb) target remote bdi10:2001 | |
145 | Remote debugging using bdi10:2001 | |
146 | 0x8ff17f10 in ?? () | |
147 | (gdb) | |
148 | ||
149 | ----------------- | |
150 | ||
151 | d) discard symbol-file | |
152 | ||
153 | (gdb) symbol-file | |
154 | Discard symbol table from `/home/hs/celf/u-boot/u-boot'? (y or n) y | |
155 | No symbol file now. | |
156 | (gdb) | |
157 | ||
158 | ----------------- | |
159 | ||
160 | e) load new symbol table: | |
161 | ||
162 | (gdb) add-symbol-file u-boot 0x8ff08000 | |
163 | add symbol table from file "u-boot" at | |
071bc923 | 164 | .text_addr = 0x8ff08000 |
f1d2b313 HS |
165 | (y or n) y |
166 | Reading symbols from /home/hs/celf/u-boot/u-boot...done. | |
167 | (gdb) c | |
168 | Continuing. | |
169 | ^C | |
170 | Program received signal SIGSTOP, Stopped (signal). | |
171 | 0x8ff17f18 in serial_getc () at serial_mxc.c:192 | |
071bc923 | 172 | 192 while (__REG(UART_PHYS + UTS) & UTS_RXEMPTY); |
f1d2b313 HS |
173 | (gdb) |
174 | ||
175 | add-symbol-file u-boot 0x8ff08000 | |
071bc923 WD |
176 | ^^^^^^^^^^ |
177 | get this address from u-boot debug printfs | |
f1d2b313 HS |
178 | |
179 | U-Boot 2010.06-rc2-00009-gf77b8b8-dirty (Jun 22 2010 - 09:43:46) | |
180 | ||
181 | U-Boot code: A0000000 -> A0058BAC BSS: -> A0061F10 | |
182 | CPU: Freescale i.MX31 at 398 MHz | |
183 | Board: DAVE/DENX Qong | |
184 | mon: FFFFFFFF gd->monLen: 00061F10 | |
185 | Top of RAM usable for U-Boot at: 90000000 | |
186 | LCD panel info: 640 x 480, 16 bit/pix | |
187 | Reserving 600k for LCD Framebuffer at: 8ff6a000 | |
188 | Reserving 391k for U-Boot at: 8ff08000 | |
071bc923 | 189 | ^^^^^^^^ |
f1d2b313 HS |
190 | Reserving 1280k for malloc() at: 8fdc8000 |
191 | Reserving 24 Bytes for Board Info at: 8fdc7fe8 | |
192 | Reserving 52 Bytes for Global Data at: 8fdc7fb4 | |
193 | New Stack Pointer is: 8fdc7fb0 | |
194 | RAM Configuration: | |
195 | Bank #0: 80000000 256 MiB | |
196 | relocation Offset is: eff08000 | |
197 | mon: 00058BAC gd->monLen: 00061F10 | |
198 | Now running in RAM - U-Boot at: 8ff08000 | |
071bc923 | 199 | ^^^^^^^^ |
f1d2b313 HS |
200 | |
201 | Now you can use gdb as usual :-) |