Difference between revisions of "The IGEP X-loader"
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</pre> | </pre> | ||
| − | It's important take a lool to the call assembly function cpu_init_crit (you can see the code below) this is resposable to call the board initialization defined in [http://git.igep.es/?p=pub/scm/igep-x-loader.git;a=blob;f=board/igep0020/platform.S platform.S] file.<br> | + | It's important take a lool to the call assembly function cpu_init_crit (you can see the code below) this is resposable to call the board initialization defined in [http://git.igep.es/?p=pub/scm/igep-x-loader.git;a=blob;f=board/igep0020/platform.S platform.S] file. Check the call to lowlevel_init:<br> |
<pre> 175 cpu_init_crit: | <pre> 175 cpu_init_crit: | ||
176 /* | 176 /* | ||
| Line 316: | Line 316: | ||
</pre> | </pre> | ||
| − | <br> | + | Lowlevel_init it's responsable to set the stack settings and call the lowlevel board initialization called s_init "C" code defined in [http://git.igep.es/?p=pub/scm/igep-x-loader.git;a=blob;f=board/igep0020/igep0020.c here]<br> |
| + | <pre> 171 .globl lowlevel_init | ||
| + | 172 lowlevel_init: | ||
| − | + | 173 ldr sp, SRAM_STACK | |
| + | |||
| + | 174 str ip, [sp] /* stash old link register */ | ||
| + | |||
| + | 175 mov ip, lr /* save link reg across call */ | ||
| + | |||
| + | 176 bl s_init /* go setup pll,mux,memory */ | ||
| + | |||
| + | 177 ldr ip, [sp] /* restore save ip */ | ||
| + | |||
| + | 178 mov lr, ip /* restore link reg */ | ||
| + | |||
| + | 179 | ||
| + | |||
| + | 180 /* back to arch calling code */ | ||
| + | |||
| + | 181 mov pc, lr | ||
| + | |||
| + | |||
| + | |||
| + | </pre> | ||
| + | At the end and after the s_init call the code jump to initial C function called [http://git.igep.es/?p=pub/scm/igep-x-loader.git;a=blob;f=lib/board.c start_armboot] defined in the file lib/board.c.<br> | ||
== C Execution Flow<br> == | == C Execution Flow<br> == | ||
Revision as of 23:15, 26 February 2011
Contents
Summary
X-Loader, an initial program loader for Embedded boards based on OMAP processors.
Features and Limitations
Improvements & Modifications
- Malloc/free functionality.
- Mtd framework and onenand support, removed the old onenand drivers.
- Jffs2 support using mtd & onenand support (Read Only).
- Crc32 and zlib.
- Jffs2 zlib compression support (Read Only).
- Dual boot mmc & onenand with mmc highest priority.
- Linux kernel boot directly (Support for 2.6.22 and highest version kernels)
- Linux kernel supported images: vmlinuz, bzImage and zImage.
- Support for loading Linux Ram disk (EXPERIMENTAL)
- "ini" files parser.
- The configuration resides in a plain txt (ini format file).
- Support Windows & Linux formating ini files.
- Boot from mmc, onenand, or mix with mmc highest priority.
- Codeblocks project and compilation rules.
- Support for gcc 4.5.1.
Limitations
- The ini configuration file it's limited to max size: 16 KiB
- Kernel Command line parameters it's limited to: 4 KiB
- Malloc it's limited to 32 MiB.
- Cannot write comments in lines with tag=value
TODO
- Support for IGEP0030 - Family boards.
- Support for other OMAP/DM/AM processor boards.
- Remove compilation warnings.
- Comments in tag lines
STATUS
- Support IGEP0020 Revision B & C family boards.
- Tested with IGEPv2 (DM3730@1Ghz and 512/512 MB Ram/Onenand)
- Tested with IGEPv2 (AM3703@1Ghz and 512/512 MB Ram/Onenand)
- Tested with IGEPv2 (OMAP3530@720Mhz and 512/512 MB Ram/Onenand)
Build Procedure
Build with Ubuntu Cross Compiler gcc 4.5.1
EnviromentUbuntu 10.10
Install the cross compiler if you not do it before.
apt-get install cpp-4.5-arm-linux-gnueabi g++-4.5-arm-linux-gnueabi
Setup the board settings
make igep0020-sdcard_config
Build
make
Sign the binary x-loader
You should execute contrib/signGP for sign the xloader.
contrib/signGP x-load.bin The signed x-loader it's named: x-load.bin.ift
Build with IGEP SDK
Setup the Enviroment
source /usr/local/poky/eabi-glibc/environment-setup-arm-none-linux-gnueabi
Setup the board settings
make igep0020-sdcard_config
Build
make CROSS_COMPILE=arm-none-linux-gnueabi-
Sign the binary x-loader
You should execute contrib/signGP for sign the xloader.
contrib/signGP x-load.bin The signed x-loader it's named: x-load.bin.ift
Build Native
Configure the board settings
make igep0020-sdcard_config
Edit the variable CFLAGS and add the option: -fno-stack-protector CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes -fno-stack-protector
Build
make CROSS_COMPILE=arm-none-linux-gnueabi-
Sign the binary x-loader
You should execute contrib/signGP for sign the xloader.
contrib/signGP x-load.bin The signed x-loader it's named: x-load.bin.ift
BOOT
The IGEP X-Loader must reside in the microSD card or in the OneNand.
Low Level Initialization
The OMAP Processor loads the XLoader directly from the mmc or the OneNand and copy the binary into the internal processor RAM (0x40200000) and jump to this place, this internal memory it's limited to 64K divided as: Interrupts, code, data and stack. Initialization code can be found using this link: start.S
96 reset:
97 /*
98 * set the cpu to SVC32 mode
99 */
100 mrs r0,cpsr
101 bic r0,r0,#0x1f
102 orr r0,r0,#0xd3
103 msr cpsr,r0
104
105 /* Copy vectors to mask ROM indirect addr */
106 adr r0, _start /* r0 <- current position of code */
107 add r0, r0, #4 /* skip reset vector */
108 mov r2, #64 /* r2 <- size to copy */
109 add r2, r0, r2 /* r2 <- source end address */
110 mov r1, #SRAM_OFFSET0 /* build vect addr */
111 mov r3, #SRAM_OFFSET1
112 add r1, r1, r3
113 mov r3, #SRAM_OFFSET2
114 add r1, r1, r3
115 next:
116 ldmia r0!, {r3-r10} /* copy from source address [r0] */
117 stmia r1!, {r3-r10} /* copy to target address [r1] */
118 cmp r0, r2 /* until source end address [r2] */
119 bne next /* loop until equal */
120
121 bl cpy_clk_code /* put dpll adjust code behind vectors */
122
123 /* the mask ROM code should have PLL and others stable */
124 bl cpu_init_crit
125
126 relocate: /* relocate U-Boot to RAM */
127 adr r0, _start /* r0 <- current position of code */
128 ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
129 cmp r0, r1 /* no need to relocate if XIP */
130 beq stack_setup /* skip txt cpy if XIP(SRAM, SDRAM) */
131
132 ldr r2, _armboot_start
133 ldr r3, _bss_start
134 sub r2, r3, r2 /* r2 <- size of armboot */
135 add r2, r0, r2 /* r2 <- source end address */
136
137 copy_loop:
138 ldmia r0!, {r3-r10} /* copy from source address [r0] */
139 stmia r1!, {r3-r10} /* copy to target address [r1] */
140 cmp r0, r2 /* until source end addreee [r2] */
141 ble copy_loop
142
143 /* Set up the stack */
144 stack_setup:
145 ldr r0, _TEXT_BASE /* upper 128 KiB: relocated uboot */
146 sub sp, r0, #128 /* leave 32 words for abort-stack */
147 and sp, sp, #~7 /* 8 byte alinged for (ldr/str)d */
148
149 /* Clear BSS (if any). Is below tx (watch load addr - need space) */
150 clear_bss:
151 ldr r0, _bss_start /* find start of bss segment */
152 ldr r1, _bss_end /* stop here */
153 mov r2, #0x00000000 /* clear value */
154 clbss_l:
155 str r2, [r0] /* clear BSS location */
156 cmp r0, r1 /* are we at the end yet */
157 add r0, r0, #4 /* increment clear index pointer */
158 bne clbss_l /* keep clearing till at end */
159
160 ldr pc, _start_armboot /* jump to C code */
161
162 _start_armboot: .word start_armboot
It's important take a lool to the call assembly function cpu_init_crit (you can see the code below) this is resposable to call the board initialization defined in platform.S file. Check the call to lowlevel_init:
175 cpu_init_crit: 176 /* 177 * Invalidate L1 I/D 178 */ 179 mov r0, #0 /* set up for MCR */ 180 mcr p15, 0, r0, c8, c7, 0 /* invalidate TLBs */ 181 mcr p15, 0, r0, c7, c5, 1 /* invalidate icache */ 182 183 /* Invalide L2 cache (gp device call point) 184 * - warning, this may have issues on EMU/HS devices 185 * this call can corrupt r0-r5 186 */ 187 mov r12, #0x1 @ set up to invalide L2 188 smi: .word 0xE1600070 @ Call SMI monitor 189 190 /* 191 * disable MMU stuff and caches 192 */ 193 mrc p15, 0, r0, c1, c0, 0 194 bic r0, r0, #0x00002000 @ clear bits 13 (--V-) 195 bic r0, r0, #0x00000007 @ clear bits 2:0 (-CAM) 196 orr r0, r0, #0x00000002 @ set bit 1 (--A-) Align 197 #ifndef CONFIG_ICACHE_OFF 198 orr r0, r0, #0x00001800 @ set bit 11,12 (---I Z---) BTB,I-Cache 199 #endif 200 mcr p15, 0, r0, c1, c0, 0 201 202 /* 203 * Jump to board specific initialization... The Mask ROM will have already initialized 204 * basic memory. Go here to bump up clock rate and handle wake up conditions. 205 */ 206 adr r0, _start /* r0 <- current position of code */ 207 ldr r1, _TEXT_BASE /* test if we run from flash or RAM */ 208 cmp r0, r1 /* pass on info about skipping some init portions */ 209 moveq r0,#0x1 /* flag to skip prcm and sdrc setup */ 210 movne r0,#0x0 211 212 mov ip, lr /* persevere link reg across call */ 213 bl lowlevel_init /* go setup pll,mux,memory */ 214 mov lr, ip /* restore link */ 215 mov pc, lr /* back to my caller */
Lowlevel_init it's responsable to set the stack settings and call the lowlevel board initialization called s_init "C" code defined in here
171 .globl lowlevel_init 172 lowlevel_init: 173 ldr sp, SRAM_STACK 174 str ip, [sp] /* stash old link register */ 175 mov ip, lr /* save link reg across call */ 176 bl s_init /* go setup pll,mux,memory */ 177 ldr ip, [sp] /* restore save ip */ 178 mov lr, ip /* restore link reg */ 179 180 /* back to arch calling code */ 181 mov pc, lr
At the end and after the s_init call the code jump to initial C function called start_armboot defined in the file lib/board.c.
C Execution Flow
cpu_init
Function: cpu_init
This function it's the responsable to do the CPU generic initialization and it's the first function called.
board_init
Function: board_init
This function it's defined per board and it's the responsable to initialize the board,
4 Settings & Configuration:
================
4.1 MMC Boot
------------
Get a new mmc and create two partitions, the first one must be fat (you can follow
this howto: http://code.google.com/p/beagleboard/wiki/LinuxBootDiskFormat)
In this first partition (boot partition) you should copy:
- x-loader.bin.ift (you must rename this file to MLO) / This is a signed image using contrib/signGP tool
* igep.ini
* Your desired kernel image.
Don't use a uImage kernel format (from uboot), only kernel formats be supported.
Compilation Example:
$make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- zImage modules
Read the kernel documentation about kernel images.
4.2 Setup igep.ini file
------------------------
# Note this format permits use the characters
# '#' and ';' as comment check file size restrictions
[kernel]
kaddress=0x80008000
;rdaddress=0x84000000
serial.low=00000001
serial.high=00000000
revision=0001
;kImageName=
;kRdImageName=
[kparams]
console=ttyS2,115200n8
;earlyprintk=serial,ttyS2,115200
mem=512M
boot_delay=0
;mpurate=800
;loglevel=7
omapfb.mode=dvi:1024x768MR-16@60
smsc911x.mac=0xb2,0xb0,0x14,0xb5,0xcd,0xde
;ubi.mtd=2
;root=ubi0:igep0020-rootfs
;rootfstype=ubifs
root=/dev/mmcblk0p2 rw rootwait
Tags Supported
---------------
[kernel] ----
* kaddress=0x80008000
Kernel copy address, you should use the same address used in kernel image
configuration. If you don't know what it means maybe it's better don't change it.
- rdaddress=0x84000000
Kernel RAM disk copy address.
If you don't know what it means maybe it's better don't change it.
- serial.low=00000001
* serial.high=00000000
Board serial Number, you can read this information using /proc/cpuinfo
- revision=0001
Board Revision ID, you can read this information using /proc/cpuinfo
- kImageName=zImage
Kernel file name, if you don't provide this tag it try to load these others:
// DEFAULT IMAGES
"zImage"
"zimage"
"vmlinuz"
"bzImage"
"bzimage"
- kRdImageName=rdimage
Kernel RAM Disk file, if you don't provide this tag it try to load these others:
// DEFAULT IMAGES
"initrd"
[kparams] ----
Kernel parameters, all these parameters are passed directly to the kernel using the
kernel command line.
kernel parameters documentation:
http://www.kernel.org/doc/Documentation/kernel-parameters.txt
http://www.kernel.org/pub/linux/kernel/people/gregkh/lkn/lkn_pdf/ch09.pdf
4.3 Boot Priority
-----------------
First try mmc and if it fails then try from OneNand.
Examples:
a) MLO (x-loader), igep.ini, zImage from MMC
If all it's present in the mmc it don't try to boot from Onenand.
b) MLO (x-loader) in MMC, igep.ini and zImage in Onenand.
If only MLO it's provided this one try to load the other information from
the Onenand.
4.4 OneNand Partition settings
-------------------------------
We suggest use minimum 3 partitions on the OneNand.
Creating 3 MTD partitions on "omap2-onenand":
0x000000000000-0x000000080000 : "X-Loader"
0x000000080000-0x000000c80000 : "Boot"
0x000000c80000-0x000020000000 : "File System"
4.4.1) Xloader partition
* Not fs formated (raw)
* Suggested size: 0x80000 (512 KiB)
* The xloader must be signed before copy it in the flash memory.
You should copy the x-loader in the firsts 4 blocks (first 512 KiB), this is not a
formated partition due the ROM not permits boot from there, you should use tools:
flash_eraseall and nandwrite for copy x-loader in the first blocks.
Suggested procedure:
nand_eraseall /dev/mtd0
nandwrite -p /dev/mtd0 <x-loader>
- Sign x-loader
You should execute contrib/signGP for sign the xloader that resides inside the flash memory.
contrib/signGP x-load.bin
The signed x-loader it's named: x-load.bin.ift
Due the Onenand 512 MiB has two dies it's necessary split the x-loader and convert it to a 1 die binary.
This is a know OMAP/DM/AM OneNand/Nand boot limitation.
This is the procedure for create the x-loader OneNand binary:
You should execute: (You can use copy paste in your console)
split -b 2K x-load.bin.ift split-
for file in `ls split-a?`; do cat $file >> x-load-ddp.bin.ift; cat $file >> x-load-ddp.bin.ift; done
This last command generate a file named x-load-ddp.bin.ift this is the x-loader for copy it in the OneNand.
4.4.2 Boot Partition
--------------------
* fs used jffs2 zlib compressed filesystem.
* Suggested size: 0xC00000 (12 MiB)
First time creation:
a) Use the same procedure described in point 4.2.1. Copy your jffs2 compressed image in the
partition, it can be a empty file.
b) Erase the partition and mount it as jffs2 filesystem then you can copy with cp command.
Next Times:
Copy the files using cp command, or edit directly.
when kernel boots you can enable mount this partition over /boot directory for access all boot content.
4.4.3 Rootfs
------------
* fs (your prefered fs supported by linux, maybe a good choice it should be ubifs)
* Size, all or you can create more partitions if you wish ... 
5 Build procedure
=================
5.1 Build with Ubuntu Cross Compiler gcc 4.5.1
- This is tested with Ubuntu 10.10
a) Install the cross compiler:
apt-get install cpp-4.5-arm-linux-gnueabi g++-4.5-arm-linux-gnueabi
b) Configure the board
make igep0020-sdcard_config
c) Build
make
d) Sign x-loader
You should execute contrib/signGP for sign the xloader that resides inside the flash memory.
contrib/signGP x-load.bin
The signed x-loader it's named: x-load.bin.ift
5.2 Build with IGEP SDK
a) Source the enviroment
source /usr/local/poky/eabi-glibc/environment-setup-arm-none-linux-gnueabi
b) Edit the file Makefile
Find the define:
And Set the variable as:
CROSS_COMPILE = arm-none-linux-gnueabi-
b) Configure the board
make igep0020-sdcard_config
c) build
make
d) Sign x-loader
You should execute contrib/signGP for sign the xloader that resides inside the flash memory.
contrib/signGP x-load.bin
The signed x-loader it's named: x-load.bin.ift
5.3 Build Native
a) Configure the board
make igep0020-sdcard_config
b) Modify the config.mk file
Edit the variable CFLAGS and add the option: -fno-stack-protector
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes -fno-stack-protector
c) build
make CROSS_COMPILE=""
d) Sign x-loader
You should execute contrib/signGP for sign the xloader that resides inside the flash memory.
contrib/signGP x-load.bin
The signed x-loader it's named: x-load.bin.ift
6 Contribution & Support & Report Bugs
======================================
Contributions to this project be welcome and you can send your patches to support@iseebcn.com
or you can use the igep forum for it.
You can access to IGEP-x-Loader repository using our git at git.igep.es
IGEP IRC Channel: http://webchat.freenode.net/?channels=igep
