ARM: add relocation support
!! This breaks support for all arm boards !!
To compile in old style, you must define
CONFIG_SYS_ARM_WITHOUT_RELOC or you can compile
with "CONFIG_SYS_ARM_WITHOUT_RELOC=1 ./MAKEALL board"
!! This define will be removed soon, so convert your
board to use relocation support
Portions of this work were supported by funding from
the CE Linux Forum.
Signed-off-by: Heiko Schocher <hs@denx.de>
Fix boot from NAND for non-ARM systems
Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/doc/README.arm-relocation b/doc/README.arm-relocation
new file mode 100644
index 0000000..6be1a12
--- /dev/null
+++ b/doc/README.arm-relocation
@@ -0,0 +1,321 @@
+To make relocation on arm working, the following changes are done:
+
+Add new compilerflag:
+
+-fPIC
+
+ -> compiler generates position independent code
+
+changes in board code:
+
+- dram_init:
+ - bd pointer is now at this point not accessible, so only
+ detect the real dramsize, and store it in gd->ram_size.
+ best detected with get_ram_size();
+ ToDo: move there also the dram initialization on boards where
+ it is possible.
+ - setup the bd_t dram bank info in the new function
+ dram_init_banksize().
+
+- board.c code is adapted from ppc code
+
+- undef CONFIG_RELOC_FIXUP_WORKS
+
+ -> cmdtabl, and subcommand table must be handled from "hand"
+ collected in section "__datarellocal_start".
+
+ - How To fixup the sections:
+
+ __datarel_start, __datarelrolocal_start, __datarellocal_start and
+ __datarelro_start
+
+ automatically? Then it should be possible to define again
+ CONFIG_RELOC_FIXUP_WORKS
+
+- irq stack setup is now not longer on a fix position, instead it is
+ calculated in board_init_f, and stored in gd->irq_sp
+
+-------------------------------------------------------------------------------------
+
+To compile a board without relocation, define CONFIG_SYS_ARM_WITHOUT_RELOC
+This possibility will removed!! So please fix your board to compile without
+CONFIG_SYS_ARM_WITHOUT_RELOC defined!!!
+
+-------------------------------------------------------------------------------------
+
+ToDo:
+
+- fill in bd_t infos (check)
+- adapt all boards
+
+- maybe adapt TEXT_BASE (this must be checked from board maintainers)
+ This *must* be done for boards, which boot from NOR flash
+
+ on other boards if TEXT_BASE = relocation baseaddr, this saves
+ one copying from u-boot code.
+
+- new function dram_init_banksize() is actual board specific. Maybe
+ we make a weak default function in arch/arm/lib/board.c ?
+
+-------------------------------------------------------------------------------------
+
+Relocation with NAND_SPL (example for the tx25):
+
+- cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE)
+ and start with code execution on this address.
+
+- The First page contains u-boot code from u-boot:nand_spl/nand_boot_fsl_nfc.c
+ which inits the dram, cpu registers, reloacte itself to TEXT_BASE and loads
+ the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution
+ @CONFIG_SYS_NAND_U_BOOT_START
+
+- This u-boot does no ram int, nor cpu register setup. Just looks
+ where it have to relocate and relocate itself to this address.
+ If relocate address = TEXT_BASE(not the same, as the TEXT_BASE
+ from the nand_spl code), no need to copy, just go on with bss clear
+ and jump to board_init_r.
+
+-------------------------------------------------------------------------------------
+
+Relocation:
+How to translate flash addresses in GOT to ram addresses.
+This is automagically done from code, but this example
+shows, how this magic code works ;-)
+(example on the qong board)
+
+Find a variable:
+
+a) search it in System.map
+(for example flash_info)
+
+a005b4c0 B BootpID
+a005b4c4 B BootpTry
+a005b4c8 b slave
+a005b4cc B flash_info
+^^^^^^^^
+a005c908 b saved_sector.4002
+a005c910 b cfi_mtd_info
+a005c9c0 b cfi_mtd_names
+a005c9d0 B mtd_table
+
+---------------------------------------
+
+b) create hexdump from u-boot code:
+
+hexdump -C u-boot > gnlmpfhex
+
+---------------------------------------
+
+c) search the variables address in the hexdump
+
+
+*
+0005fc80 00 00 00 00 00 00 00 00 2c 06 01 a0 18 cd 05 a0 |........,.......|
+0005fc90 9c d4 05 a0 bc b4 05 a0 1c 7f 05 a0 f0 05 01 a0 |................|
+0005fca0 08 5a 04 a0 1c ab 05 a0 ec a4 05 a0 98 c3 01 a0 |.Z..............|
+0005fcb0 a0 d6 05 a0 04 71 05 a0 c0 f9 00 a0 3c cd 05 a0 |.....q......<...|
+0005fcc0 cc b4 05 a0 f0 fa 00 a0 f0 d6 05 a0 10 86 05 a0 |................|
+ ^^^^^^^^^^^
+0005fcd0 a4 16 06 a0 dc 64 05 a0 18 86 05 a0 52 48 05 a0 |.....d......RH..|
+0005fce0 c0 86 05 a0 24 6e 02 a0 b4 6c 05 a0 b0 94 01 a0 |....$n...l......|
+0005fcf0 1c 86 05 a0 50 85 05 a0 d4 0c 06 a0 bc 0b 06 a0 |....P...........|
+
+
+-> 0005fcc0
+
+----------------------------------------
+
+d) know we calculate this address in RAM
+
+
+ 8ff08000 (new address of code in RAM *1)
+
++ 0005fcc0
+
+- 00008000 (offset of text *2)
+
+----------
+
+ 8ff5fcc0 -> Addr GOT in RAM
+
+*1:
+activate debug and look for the line:
+Now running in RAM - U-Boot at: 8ff08000
+ ^^^^^^^^
+ new address of u-boot code in RAM
+
+*2:
+Section Headers:
+ [Nr] Name Type Addr Off Size ES Flg Lk Inf Al
+ [ 0] NULL 00000000 000000 000000 00 0 0 0
+ [ 1] .text PROGBITS a0000000 008000 04599c 00 AX 0 0 32
+ ^^^^^^
+ Offset of text
+
+----------------------------------------
+
+e) now we look in 8ff5fcc0 (RAM)
+
+
+QongEVB>md 0x8ff5fcc0
+8ff5fcc0 : a005b4cc a000faf0 a005d6f0 a0058610 ................
+ ^^^^^^^^
+ Bingo, here we have the old flash address (when relocation
+ is working, here is the fixed ram address. see @ f, how
+ it gets calculated)
+
+
+----------------------------------------
+
+f) now translate it in the new RAM address
+
+ a005b4cc
+
+- a0000000 TextBase
+
++ 8ff08000 new address of u-boot in ram
+----------
+ 8ff634cc
+
+QongEVB>mm 0x8ff5fcc0 0x8ff634cc 1
+QongEVB>md 0x8ff5fcc0
+8ff5fcc0 : 8ff634cc a000faf0 a005d6f0 a0058610 .4..............
+8ff5fcd0 : a00616a4 a00564dc a0058618 a0054852 .....d......RH..
+
+As this must be done for all address in the GOT, the u-boot
+code did this automagically ... :-)
+
+----------------------------------------------
+
+g) check if the new address is really in the bss section:
+
+bss start:
+8ff6054c (8ff08000 + 0005854C monitorlen)
+
+bss end:
+8ff698ac (8ff08000 + 618AC)
+
+8ff634cc is in bss :-)
+
+----------------------------------------------
+
+h) u-boot prints:
+
+important addresses:
+
+U-Boot code: A0000000 -> A005854C BSS: -> A00618AC TextBase 0xa0000000
+Now running in RAM - U-Boot at: 8ff08000 relocBase 0x8ff08000
+
+
+---------
+
+U-Boot 2010.06-rc2-00002-gf8fbb25-dirty (Jun 18 2010 - 17:07:19)
+
+U-Boot code: A0000000 -> A005854C BSS: -> A00618AC
+CPU: Freescale i.MX31 at 398 MHz
+Board: DAVE/DENX Qong
+mon: FFFFFFFF gd->monLen: 000618AC
+Top of RAM usable for U-Boot at: 90000000
+LCD panel info: 640 x 480, 16 bit/pix
+Reserving 600k for LCD Framebuffer at: 8ff6a000
+Reserving 390k for U-Boot at: 8ff08000
+Reserving 1280k for malloc() at: 8fdc8000
+Reserving 28 Bytes for Board Info at: 8fdc7fe4
+Reserving 48 Bytes for Global Data at: 8fdc7fb4
+New Stack Pointer is: 8fdc7fb0
+RAM Configuration:
+Bank #0: 80000000 256 MiB
+mon: 0005854C gd->monLen: 000618AC
+Now running in RAM - U-Boot at: 8ff08000
+
+-------------------------------------------------------------------------------------
+
+Debugging u-boot in RAM:
+(example on the qong board)
+
+a) add in config.mk:
+
+PLATFORM_CPPFLAGS += -DDEBUG
+
+-----------------
+
+b) start debugger
+
+arm-linux-gdb u-boot
+
+[hs@pollux u-boot]$ arm-linux-gdb u-boot
+GNU gdb Red Hat Linux (6.7-2rh)
+Copyright (C) 2007 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law. Type "show copying"
+and "show warranty" for details.
+This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-linux".
+The target architecture is set automatically (currently arm)
+..
+(gdb)
+
+-----------------
+
+c) connect to target
+
+target remote bdi10:2001
+
+(gdb) target remote bdi10:2001
+Remote debugging using bdi10:2001
+0x8ff17f10 in ?? ()
+(gdb)
+
+-----------------
+
+d) discard symbol-file
+
+(gdb) symbol-file
+Discard symbol table from `/home/hs/celf/u-boot/u-boot'? (y or n) y
+No symbol file now.
+(gdb)
+
+-----------------
+
+e) load new symbol table:
+
+(gdb) add-symbol-file u-boot 0x8ff08000
+add symbol table from file "u-boot" at
+ .text_addr = 0x8ff08000
+(y or n) y
+Reading symbols from /home/hs/celf/u-boot/u-boot...done.
+(gdb) c
+Continuing.
+^C
+Program received signal SIGSTOP, Stopped (signal).
+0x8ff17f18 in serial_getc () at serial_mxc.c:192
+192 while (__REG(UART_PHYS + UTS) & UTS_RXEMPTY);
+(gdb)
+
+add-symbol-file u-boot 0x8ff08000
+ ^^^^^^^^^^
+ get this address from u-boot debug printfs
+
+U-Boot 2010.06-rc2-00009-gf77b8b8-dirty (Jun 22 2010 - 09:43:46)
+
+U-Boot code: A0000000 -> A0058BAC BSS: -> A0061F10
+CPU: Freescale i.MX31 at 398 MHz
+Board: DAVE/DENX Qong
+mon: FFFFFFFF gd->monLen: 00061F10
+Top of RAM usable for U-Boot at: 90000000
+LCD panel info: 640 x 480, 16 bit/pix
+Reserving 600k for LCD Framebuffer at: 8ff6a000
+Reserving 391k for U-Boot at: 8ff08000
+ ^^^^^^^^
+Reserving 1280k for malloc() at: 8fdc8000
+Reserving 24 Bytes for Board Info at: 8fdc7fe8
+Reserving 52 Bytes for Global Data at: 8fdc7fb4
+New Stack Pointer is: 8fdc7fb0
+RAM Configuration:
+Bank #0: 80000000 256 MiB
+relocation Offset is: eff08000
+mon: 00058BAC gd->monLen: 00061F10
+Now running in RAM - U-Boot at: 8ff08000
+ ^^^^^^^^
+
+Now you can use gdb as usual :-)