一般 soc 都會提供 u-boot 來當作 bootloader, 不過 rpi2 並沒有, u-boot 有很多豐富的功能, 在操作 rpi2 時, 也許有額外的助益, 來看看怎麼安裝 u-boot。
ref:
http://elinux.org/RPi_U-Boot
git clone git://github.com/swarren/u-boot.git
git checkout -b rpi_dev origin/rpi_dev
git clone git://git.denx.de/u-boot.git
make rpi_2_defconfig
make
cp u-boot.bin /sd_card/part1
cp /sd_card/part1/config.txt /sd_card/part1/config.txt.bak
echo 'kernel=u-boot.bin' > /sd_card/part1/config.txt
u-boot 環境變數
dhcpuboot=usb start; dhcp u-boot.uimg; bootm
distro_bootcmd=for target in ${boot_targets}; do run bootcmd_${target}; done
fdt_addr_r=0x02000000
fdtfile=bcm2836-rpi-2-b.dtb
kernel_addr_r=0x01000000
loadaddr=0x00200000
mmc_boot=if mmc dev ${devnum}; then setenv devtype mmc; run scan_dev_for_boot_part; fi
pxefile_addr_r=0x00100000
ramdisk_addr_r=0x02100000
scan_dev_for_boot=echo Scanning ${devtype} ${devnum}:${bootpart}...; for prefix in ${boot_prefixes}; do rune
scan_dev_for_boot_part=part list ${devtype} ${devnum} -bootable devplist; env exists devplist || setenv deve
scan_dev_for_extlinux=if test -e ${devtype} ${devnum}:${bootpart} ${prefix}extlinux/extlinux.conf; then echi
scan_dev_for_scripts=for script in ${boot_scripts}; do if test -e ${devtype} ${devnum}:${bootpart} ${prefixe
scriptaddr=0x00000000
soc=bcm283x
stderr=serial,lcd
stdin=serial,usbkbd
stdout=serial,lcd
usb_boot=usb start; if usb dev ${devnum}; then setenv devtype usb; run scan_dev_for_boot_part; fi
usbethaddr=b8:27:eb:90:b1:7b
vendor=raspberrypi
可以用 uart 接出來看到 u-boot 畫面。當然電視的畫面也有, 不過有點歪歪的就是。
u-boot 畫面
zImage 是我自己編譯出來的 kernel, 複製到 sdcard 上, 使用以下 u-boot 指令載入 kernel:
載入 linux
1 # Tell Linux that it is booting on a Raspberry Pi2
2 setenv machid 0x00000c42
3 # Set the kernel boot command line
4 setenv bootargs "earlyprintk console=tty0 console=ttyAMA0 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait noinitrd"
5 # Save these changes to u-boot's environment
6 saveenv
7 # Load the existing Linux kernel into RAM
8 fatload mmc 0:1 ${kernel_addr_r} zImage
9 # Boot the kernel we have just loaded
10 bootz ${kernel_addr_r}
u-boot 已經愈來愈複雜了, 熟悉它不是壞事, 很多 soc 有提供了 u-boot, 也提供很複雜的載入指令, 在接觸到其他 soc 時, 就不會那麼陌生。
20230210 補充:
另外隨著 qemu (QEMU emulator version 7.2.0 (Debian 1:7.2+dfsg-2) ) 的開發, 目前也有 rpi2 的模擬器, 可以執行這個 u-boot, 但是時靈時不靈, 運氣好 u-boot 可以跑起來, 如 list 1。
qemu-system-arm -machine raspi2b -no-reboot -nographic -kernel ./u-boot
list 1. u-boot on qemu rpi2
1 descent@debian-vm:u-boot$ ./qu.sh
2
3 U-Boot 2023.04-rc1-00335-gd1f5dbe664 (Feb 09 2023 - 15:12:42 +0800)
4
5 DRAM: 960 MiB
6 RPI 2 Model B (0xa21041)
7 Core: 63 devices, 14 uclasses, devicetree: embed
8 MMC: mmc@7e202000: 0
9 Loading Environment from FAT... WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
10 WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
11 Card did not respond to voltage select! : -110
12 ** Bad device specification mmc 0 **
13 In: serial
14 Out: vidconsole
15 Err: vidconsole
16 Net: No ethernet found.
17 starting USB...
18 Bus usb@7e980000: USB DWC2
19 scanning bus usb@7e980000 for devices... 1 USB Device(s) found
20 scanning usb for storage devices... 0 Storage Device(s) found
21 Hit any key to stop autoboot: 0
22 WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
23 WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
24 WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
25 Card did not respond to voltage select! : -110
26 MMC Device 1 not found
27 no mmc device at slot 1
28 MMC Device 2 not found
29 no mmc device at slot 2
30
31 Device 0: unknown device
32 No ethernet found.
33 missing environment variable: pxeuuid
34 Retrieving file: pxelinux.cfg/00000000
35 No ethernet found.
36 Retrieving file: pxelinux.cfg/0000000
37 No ethernet found.
38 Retrieving file: pxelinux.cfg/000000
39 No ethernet found.
40 Retrieving file: pxelinux.cfg/00000
41 No ethernet found.
42 Retrieving file: pxelinux.cfg/0000
43 No ethernet found.
44 Retrieving file: pxelinux.cfg/000
45 No ethernet found.
46 Retrieving file: pxelinux.cfg/00
47 No ethernet found.
48 Retrieving file: pxelinux.cfg/0
49 No ethernet found.
50 Retrieving file: pxelinux.cfg/default-arm-bcm283x-rpi
51 No ethernet found.
52 Retrieving file: pxelinux.cfg/default-arm-bcm283x
53 No ethernet found.
54 Retrieving file: pxelinux.cfg/default-arm
55 No ethernet found.
56 Retrieving file: pxelinux.cfg/default
57 No ethernet found.
58 Config file not found
59 No ethernet found.
60 No ethernet found.
61 U-Boot> help
62 ? - alias for 'help'
63 base - print or set address offset
64 bdinfo - print Board Info structure
65 blkcache - block cache diagnostics and control
66 boot - boot default, i.e., run 'bootcmd'
67 bootd - boot default, i.e., run 'bootcmd'
68 bootefi - Boots an EFI payload from memory
69 bootelf - Boot from an ELF image in memory
70 bootflow - Boot flows
71 bootm - boot application image from memory
72 bootp - boot image via network using BOOTP/TFTP protocol
73 bootvx - Boot vxWorks from an ELF image
74 bootz - boot Linux zImage image from memory
75 cls - clear screen
76 cmp - memory compare
77 coninfo - print console devices and information
78 cp - memory copy
79 crc32 - checksum calculation
80 dhcp - boot image via network using DHCP/TFTP protocol
81 dm - Driver model low level access
82 echo - echo args to console
83 editenv - edit environment variable
84 env - environment handling commands
85 exit - exit script
86 ext2load - load binary file from a Ext2 filesystem
87 ext2ls - list files in a directory (default /)
88 ext4load - load binary file from a Ext4 filesystem
89 ext4ls - list files in a directory (default /)
90 ext4size - determine a file's size
91 false - do nothing, unsuccessfully
92 fatinfo - print information about filesystem
93 fatload - load binary file from a dos filesystem
94 fatls - list files in a directory (default /)
95 fatmkdir - create a directory
96 fatrm - delete a file
97 fatsize - determine a file's size
98 fatwrite - write file into a dos filesystem
99 fdt - flattened device tree utility commands
100 fstype - Look up a filesystem type
101 fstypes - List supported filesystem types
102 fsuuid - Look up a filesystem UUID
103 go - start application at address 'addr'
104 gpio - query and control gpio pins
105 help - print command description/usage
106 iminfo - print header information for application image
107 imxtract - extract a part of a multi-image
108 itest - return true/false on integer compare
109 lcdputs - print string on video framebuffer
110 ln - Create a symbolic link
111 load - load binary file from a filesystem
112 loadb - load binary file over serial line (kermit mode)
113 loads - load S-Record file over serial line
114 loadx - load binary file over serial line (xmodem mode)
115 loady - load binary file over serial line (ymodem mode)
116 loop - infinite loop on address range
117 ls - list files in a directory (default /)
118 md - memory display
119 mii - MII utility commands
120 mm - memory modify (auto-incrementing address)
121 mmc - MMC sub system
122 mmcinfo - display MMC info
123 mw - memory write (fill)
124 net - NET sub-system
125 nfs - boot image via network using NFS protocol
126 nm - memory modify (constant address)
127 panic - Panic with optional message
128 part - disk partition related commands
129 ping - send ICMP ECHO_REQUEST to network host
130 pinmux - show pin-controller muxing
131 printenv - print environment variables
132 pxe - commands to get and boot from pxe files
133 random - fill memory with random pattern
134 reset - Perform RESET of the CPU
135 run - run commands in an environment variable
136 save - save file to a filesystem
137 saveenv - save environment variables to persistent storage
138 setcurs - set cursor position within screen
139 setenv - set environment variables
140 setexpr - set environment variable as the result of eval expression
141 showvar - print local hushshell variables
142 size - determine a file's size
143 sleep - delay execution for some time
144 source - run script from memory
145 sysboot - command to get and boot from syslinux files
146 test - minimal test like /bin/sh
147 tftpboot - load file via network using TFTP protocol
148 true - do nothing, successfully
149 usb - USB sub-system
150 usbboot - boot from USB device
151 version - print monitor, compiler and linker version
152 U-Boot>
list 2. bdinfo
1 U-Boot> bdinfo
2 boot_params = 0x00000100
3 DRAM bank = 0x00000000
4 -> start = 0x00000000
5 -> size = 0x3c000000
6 flashstart = 0x00000000
7 flashsize = 0x00000000
8 flashoffset = 0x00000000
9 baudrate = 115200 bps
10 relocaddr = 0x3bf70000
11 reloc off = 0x3bf68000
12 Build = 32-bit
13 current eth = unknown
14 ethaddr = 52:54:00:12:34:57
15 IP addr = <NULL>
16 fdt_blob = 0x00073510
17 new_fdt = 0x00000000
18 fdt_size = 0x00000000
19 Video = hdmi@7e902000 active
20 FB base = 0x3c100000
21 FB size = 640x480x32
22 lmb_dump_all:
23 memory.cnt = 0x1
24 memory[0] [0x0-0x3bffffff], 0x3c000000 bytes flags: 0
25 reserved.cnt = 0x3
26 reserved[0] [0x0-0xfff], 0x00001000 bytes flags: 0
27 reserved[1] [0x3ab67000-0x3bffffff], 0x01499000 bytes flags: 0
28 reserved[2] [0x3bb67b90-0x3bffffff], 0x00498470 bytes flags: 0
29 devicetree = embed
30 arch_number = 0x00000000
31 TLB addr = 0x3bff0000
32 irq_sp = 0x3bb6bea0
33 sp start = 0x3bb6be90
34 Early malloc usage: 374 / 400
35 U-Boot>
ref:
Booting a Raspberry Pi2, with u-boot and HYP enabled
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