1 To make relocation on arm working, the following changes are done:
7 -> compiler generates position independent code
12 - bd pointer is now at this point not accessible, so only
13 detect the real dramsize, and store it in gd->ram_size.
14 best detected with get_ram_size();
15 ToDo: move there also the dram initialization on boards where
17 - setup the bd_t dram bank info in the new function
20 - board.c code is adapted from ppc code
22 - undef CONFIG_RELOC_FIXUP_WORKS
24 -> cmdtabl, and subcommand table must be handled from "hand"
25 collected in section "__datarellocal_start".
27 - How To fixup the sections:
29 __datarel_start, __datarelrolocal_start, __datarellocal_start and
32 automatically? Then it should be possible to define again
33 CONFIG_RELOC_FIXUP_WORKS
35 - irq stack setup is now not longer on a fix position, instead it is
36 calculated in board_init_f, and stored in gd->irq_sp
38 -------------------------------------------------------------------------------------
40 To compile a board without relocation, define CONFIG_SYS_ARM_WITHOUT_RELOC
41 This possibility will removed!! So please fix your board to compile without
42 CONFIG_SYS_ARM_WITHOUT_RELOC defined!!!
44 -------------------------------------------------------------------------------------
48 - fill in bd_t infos (check)
51 - maybe adapt TEXT_BASE (this must be checked from board maintainers)
52 This *must* be done for boards, which boot from NOR flash
54 on other boards if TEXT_BASE = relocation baseaddr, this saves
55 one copying from u-boot code.
57 - new function dram_init_banksize() is actual board specific. Maybe
58 we make a weak default function in arch/arm/lib/board.c ?
60 -------------------------------------------------------------------------------------
62 Relocation with NAND_SPL (example for the tx25):
64 - cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE)
65 and start with code execution on this address.
67 - The First page contains u-boot code from u-boot:nand_spl/nand_boot_fsl_nfc.c
68 which inits the dram, cpu registers, reloacte itself to TEXT_BASE and loads
69 the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution
70 @CONFIG_SYS_NAND_U_BOOT_START
72 - This u-boot does no ram int, nor cpu register setup. Just looks
73 where it have to relocate and relocate itself to this address.
74 If relocate address = TEXT_BASE(not the same, as the TEXT_BASE
75 from the nand_spl code), no need to copy, just go on with bss clear
76 and jump to board_init_r.
78 -------------------------------------------------------------------------------------
81 How to translate flash addresses in GOT to ram addresses.
82 This is automagically done from code, but this example
83 shows, how this magic code works ;-)
84 (example on the qong board)
88 a) search it in System.map
89 (for example flash_info)
96 a005c908 b saved_sector.4002
97 a005c910 b cfi_mtd_info
98 a005c9c0 b cfi_mtd_names
101 ---------------------------------------
103 b) create hexdump from u-boot code:
105 hexdump -C u-boot > gnlmpfhex
107 ---------------------------------------
109 c) search the variables address in the hexdump
113 0005fc80 00 00 00 00 00 00 00 00 2c 06 01 a0 18 cd 05 a0 |........,.......|
114 0005fc90 9c d4 05 a0 bc b4 05 a0 1c 7f 05 a0 f0 05 01 a0 |................|
115 0005fca0 08 5a 04 a0 1c ab 05 a0 ec a4 05 a0 98 c3 01 a0 |.Z..............|
116 0005fcb0 a0 d6 05 a0 04 71 05 a0 c0 f9 00 a0 3c cd 05 a0 |.....q......<...|
117 0005fcc0 cc b4 05 a0 f0 fa 00 a0 f0 d6 05 a0 10 86 05 a0 |................|
119 0005fcd0 a4 16 06 a0 dc 64 05 a0 18 86 05 a0 52 48 05 a0 |.....d......RH..|
120 0005fce0 c0 86 05 a0 24 6e 02 a0 b4 6c 05 a0 b0 94 01 a0 |....$n...l......|
121 0005fcf0 1c 86 05 a0 50 85 05 a0 d4 0c 06 a0 bc 0b 06 a0 |....P...........|
126 ----------------------------------------
128 d) know we calculate this address in RAM
131 8ff08000 (new address of code in RAM *1)
135 - 00008000 (offset of text *2)
139 8ff5fcc0 -> Addr GOT in RAM
142 activate debug and look for the line:
143 Now running in RAM - U-Boot at: 8ff08000
145 new address of u-boot code in RAM
149 [Nr] Name Type Addr Off Size ES Flg Lk Inf Al
150 [ 0] NULL 00000000 000000 000000 00 0 0 0
151 [ 1] .text PROGBITS a0000000 008000 04599c 00 AX 0 0 32
155 ----------------------------------------
157 e) now we look in 8ff5fcc0 (RAM)
160 QongEVB>md 0x8ff5fcc0
161 8ff5fcc0 : a005b4cc a000faf0 a005d6f0 a0058610 ................
163 Bingo, here we have the old flash address (when relocation
164 is working, here is the fixed ram address. see @ f, how
168 ----------------------------------------
170 f) now translate it in the new RAM address
176 + 8ff08000 new address of u-boot in ram
180 QongEVB>mm 0x8ff5fcc0 0x8ff634cc 1
181 QongEVB>md 0x8ff5fcc0
182 8ff5fcc0 : 8ff634cc a000faf0 a005d6f0 a0058610 .4..............
183 8ff5fcd0 : a00616a4 a00564dc a0058618 a0054852 .....d......RH..
185 As this must be done for all address in the GOT, the u-boot
186 code did this automagically ... :-)
188 ----------------------------------------------
190 g) check if the new address is really in the bss section:
193 8ff6054c (8ff08000 + 0005854C monitorlen)
196 8ff698ac (8ff08000 + 618AC)
198 8ff634cc is in bss :-)
200 ----------------------------------------------
206 U-Boot code: A0000000 -> A005854C BSS: -> A00618AC TextBase 0xa0000000
207 Now running in RAM - U-Boot at: 8ff08000 relocBase 0x8ff08000
212 U-Boot 2010.06-rc2-00002-gf8fbb25-dirty (Jun 18 2010 - 17:07:19)
214 U-Boot code: A0000000 -> A005854C BSS: -> A00618AC
215 CPU: Freescale i.MX31 at 398 MHz
216 Board: DAVE/DENX Qong
217 mon: FFFFFFFF gd->monLen: 000618AC
218 Top of RAM usable for U-Boot at: 90000000
219 LCD panel info: 640 x 480, 16 bit/pix
220 Reserving 600k for LCD Framebuffer at: 8ff6a000
221 Reserving 390k for U-Boot at: 8ff08000
222 Reserving 1280k for malloc() at: 8fdc8000
223 Reserving 28 Bytes for Board Info at: 8fdc7fe4
224 Reserving 48 Bytes for Global Data at: 8fdc7fb4
225 New Stack Pointer is: 8fdc7fb0
227 Bank #0: 80000000 256 MiB
228 mon: 0005854C gd->monLen: 000618AC
229 Now running in RAM - U-Boot at: 8ff08000
231 -------------------------------------------------------------------------------------
233 Debugging u-boot in RAM:
234 (example on the qong board)
238 PLATFORM_CPPFLAGS += -DDEBUG
246 [hs@pollux u-boot]$ arm-linux-gdb u-boot
247 GNU gdb Red Hat Linux (6.7-2rh)
248 Copyright (C) 2007 Free Software Foundation, Inc.
249 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
250 This is free software: you are free to change and redistribute it.
251 There is NO WARRANTY, to the extent permitted by law. Type "show copying"
252 and "show warranty" for details.
253 This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-linux".
254 The target architecture is set automatically (currently arm)
262 target remote bdi10:2001
264 (gdb) target remote bdi10:2001
265 Remote debugging using bdi10:2001
271 d) discard symbol-file
274 Discard symbol table from `/home/hs/celf/u-boot/u-boot'? (y or n) y
280 e) load new symbol table:
282 (gdb) add-symbol-file u-boot 0x8ff08000
283 add symbol table from file "u-boot" at
284 .text_addr = 0x8ff08000
286 Reading symbols from /home/hs/celf/u-boot/u-boot...done.
290 Program received signal SIGSTOP, Stopped (signal).
291 0x8ff17f18 in serial_getc () at serial_mxc.c:192
292 192 while (__REG(UART_PHYS + UTS) & UTS_RXEMPTY);
295 add-symbol-file u-boot 0x8ff08000
297 get this address from u-boot debug printfs
299 U-Boot 2010.06-rc2-00009-gf77b8b8-dirty (Jun 22 2010 - 09:43:46)
301 U-Boot code: A0000000 -> A0058BAC BSS: -> A0061F10
302 CPU: Freescale i.MX31 at 398 MHz
303 Board: DAVE/DENX Qong
304 mon: FFFFFFFF gd->monLen: 00061F10
305 Top of RAM usable for U-Boot at: 90000000
306 LCD panel info: 640 x 480, 16 bit/pix
307 Reserving 600k for LCD Framebuffer at: 8ff6a000
308 Reserving 391k for U-Boot at: 8ff08000
310 Reserving 1280k for malloc() at: 8fdc8000
311 Reserving 24 Bytes for Board Info at: 8fdc7fe8
312 Reserving 52 Bytes for Global Data at: 8fdc7fb4
313 New Stack Pointer is: 8fdc7fb0
315 Bank #0: 80000000 256 MiB
316 relocation Offset is: eff08000
317 mon: 00058BAC gd->monLen: 00061F10
318 Now running in RAM - U-Boot at: 8ff08000
321 Now you can use gdb as usual :-)