| By Vlad Lungu vlad.lungu@windriver.com 2007-Oct-01 | |
| ---------------------------------------- | |
| Qemu is a full system emulator. See | |
| http://www.nongnu.org/qemu/ | |
| Limitations & comments | |
| ---------------------- | |
| Supports the "-M mips" configuration of qemu: serial,NE2000,IDE. | |
| Supports little and big endian as well as 32 bit and 64 bit. | |
| Derived from au1x00 with a lot of things cut out. | |
| Supports emulated flash (patch Jean-Christophe PLAGNIOL-VILLARD) with | |
| recent qemu versions. When using emulated flash, launch with | |
| -pflash <filename> and erase mips_bios.bin. | |
| Notes for the Qemu MIPS port | |
| ---------------------------- | |
| I) Example usage: | |
| Using u-boot.bin as ROM (replaces Qemu monitor): | |
| 32 bit, big endian: | |
| # make qemu_mips | |
| # qemu-system-mips -M mips -bios u-boot.bin -nographic | |
| 32 bit, little endian: | |
| # make qemu_mipsel | |
| # qemu-system-mipsel -M mips -bios u-boot.bin -nographic | |
| 64 bit, big endian: | |
| # make qemu_mips64 | |
| # qemu-system-mips64 -cpu MIPS64R2-generic -M mips -bios u-boot.bin -nographic | |
| 64 bit, little endian: | |
| # make qemu_mips64el | |
| # qemu-system-mips64el -cpu MIPS64R2-generic -M mips -bios u-boot.bin -nographic | |
| or using u-boot.bin from emulated flash: | |
| if you use a qemu version after commit 4224 | |
| create image: | |
| # dd of=flash bs=1k count=4k if=/dev/zero | |
| # dd of=flash bs=1k conv=notrunc if=u-boot.bin | |
| start it (see above): | |
| # qemu-system-mips[64][el] [-cpu MIPS64R2-generic] -M mips -pflash flash -nographic | |
| 2) Download kernel + initrd | |
| On ftp://ftp.denx.de/pub/contrib/Jean-Christophe_Plagniol-Villard/qemu_mips/ | |
| you can downland | |
| #config to build the kernel | |
| qemu_mips_defconfig | |
| #patch to fix mips interrupt init on 2.6.24.y kernel | |
| qemu_mips_kernel.patch | |
| initrd.gz | |
| vmlinux | |
| vmlinux.bin | |
| System.map | |
| 4) Generate uImage | |
| # tools/mkimage -A mips -O linux -T kernel -C gzip -a 0x80010000 -e 0x80245650 -n "Linux 2.6.24.y" -d vmlinux.bin.gz uImage | |
| 5) Copy uImage to Flash | |
| # dd if=uImage bs=1k conv=notrunc seek=224 of=flash | |
| 6) Generate Ide Disk | |
| # dd of=ide bs=1k cout=100k if=/dev/zero | |
| # sfdisk -C 261 -d ide | |
| # partition table of ide | |
| unit: sectors | |
| ide1 : start= 63, size= 32067, Id=83 | |
| ide2 : start= 32130, size= 32130, Id=83 | |
| ide3 : start= 64260, size= 4128705, Id=83 | |
| ide4 : start= 0, size= 0, Id= 0 | |
| 7) Copy to ide | |
| # dd if=uImage bs=512 conv=notrunc seek=63 of=ide | |
| 8) Generate ext2 on part 2 on Copy uImage and initrd.gz | |
| # Attached as loop device ide offset = 32130 * 512 | |
| # losetup -o 16450560 -f ide | |
| # Format as ext2 ( arg2 : nb blocks) | |
| # mke2fs /dev/loop0 16065 | |
| # losetup -d /dev/loop0 | |
| # Mount and copy uImage and initrd.gz to it | |
| # mount -o loop,offset=16450560 -t ext2 ide /mnt | |
| # mkdir /mnt/boot | |
| # cp {initrd.gz,uImage} /mnt/boot/ | |
| # Umount it | |
| # umount /mnt | |
| 9) Set Environment | |
| setenv rd_start 0x80800000 | |
| setenv rd_size 2663940 | |
| setenv kernel BFC38000 | |
| setenv oad_addr 80500000 | |
| setenv load_addr2 80F00000 | |
| setenv kernel_flash BFC38000 | |
| setenv load_addr_hello 80200000 | |
| setenv bootargs 'root=/dev/ram0 init=/bin/sh' | |
| setenv load_rd_ext2 'ide res; ext2load ide 0:2 ${rd_start} /boot/initrd.gz' | |
| setenv load_rd_tftp 'tftp ${rd_start} /initrd.gz' | |
| setenv load_kernel_hda 'ide res; diskboot ${load_addr} 0:2' | |
| setenv load_kernel_ext2 'ide res; ext2load ide 0:2 ${load_addr} /boot/uImage' | |
| setenv load_kernel_tftp 'tftp ${load_addr} /qemu_mips/uImage' | |
| setenv boot_ext2_ext2 'run load_rd_ext2; run load_kernel_ext2; run addmisc; bootm ${load_addr}' | |
| setenv boot_ext2_flash 'run load_rd_ext2; run addmisc; bootm ${kernel_flash}' | |
| setenv boot_ext2_hda 'run load_rd_ext2; run load_kernel_hda; run addmisc; bootm ${load_addr}' | |
| setenv boot_ext2_tftp 'run load_rd_ext2; run load_kernel_tftp; run addmisc; bootm ${load_addr}' | |
| setenv boot_tftp_hda 'run load_rd_tftp; run load_kernel_hda; run addmisc; bootm ${load_addr}' | |
| setenv boot_tftp_ext2 'run load_rd_tftp; run load_kernel_ext2; run addmisc; bootm ${load_addr}' | |
| setenv boot_tftp_flash 'run load_rd_tftp; run addmisc; bootm ${kernel_flash}' | |
| setenv boot_tftp_tftp 'run load_rd_tftp; run load_kernel_tftp; run addmisc; bootm ${load_addr}' | |
| setenv load_hello_tftp 'tftp ${load_addr_hello} /examples/hello_world.bin' | |
| setenv go_tftp 'run load_hello_tftp; go ${load_addr_hello}' | |
| setenv addmisc 'setenv bootargs ${bootargs} console=ttyS0,${baudrate} rd_start=${rd_start} rd_size=${rd_size} ethaddr=${ethaddr}' | |
| setenv bootcmd 'run boot_tftp_flash' | |
| 10) Now you can boot from flash, ide, ide+ext2 and tfp | |
| # qemu-system-mips -M mips -pflash flash -monitor null -nographic -net nic -net user -tftp `pwd` -hda ide | |
| II) How to debug U-Boot | |
| In order to debug U-Boot you need to start qemu with gdb server support (-s) | |
| and waiting the connection to start the CPU (-S) | |
| # qemu-system-mips -S -s -M mips -pflash flash -monitor null -nographic -net nic -net user -tftp `pwd` -hda ide | |
| in an other console you start gdb | |
| 1) Debugging of U-Boot Before Relocation | |
| Before relocation, the addresses in the ELF file can be used without any problems | |
| by connecting to the gdb server localhost:1234 | |
| # mipsel-unknown-linux-gnu-gdb u-boot | |
| GNU gdb 6.6 | |
| Copyright (C) 2006 Free Software Foundation, Inc. | |
| GDB is free software, covered by the GNU General Public License, and you are | |
| welcome to change it and/or distribute copies of it under certain conditions. | |
| Type "show copying" to see the conditions. | |
| There is absolutely no warranty for GDB. Type "show warranty" for details. | |
| This GDB was configured as "--host=i486-linux-gnu --target=mipsel-unknown-linux-gnu"... | |
| (gdb) target remote localhost:1234 | |
| Remote debugging using localhost:1234 | |
| _start () at start.S:64 | |
| 64 RVECENT(reset,0) /* U-boot entry point */ | |
| Current language: auto; currently asm | |
| (gdb) b board.c:289 | |
| Breakpoint 1 at 0xbfc00cc8: file board.c, line 289. | |
| (gdb) c | |
| Continuing. | |
| Breakpoint 1, board_init_f (bootflag=<value optimized out>) at board.c:290 | |
| 290 relocate_code (addr_sp, id, addr); | |
| Current language: auto; currently c | |
| (gdb) p/x addr | |
| $1 = 0x87fa0000 | |
| 2) Debugging of U-Boot After Relocation | |
| For debugging U-Boot after relocation we need to know the address to which | |
| U-Boot relocates itself to 0x87fa0000 by default. | |
| And replace the symbol table to this offset. | |
| (gdb) symbol-file | |
| Discard symbol table from `/private/u-boot-arm/u-boot'? (y or n) y | |
| Error in re-setting breakpoint 1: | |
| No symbol table is loaded. Use the "file" command. | |
| No symbol file now. | |
| (gdb) add-symbol-file u-boot 0x87fa0000 | |
| add symbol table from file "u-boot" at | |
| .text_addr = 0x87fa0000 | |
| (y or n) y | |
| Reading symbols from /private/u-boot-arm/u-boot...done. | |
| Breakpoint 1 at 0x87fa0cc8: file board.c, line 289. | |
| (gdb) c | |
| Continuing. | |
| Program received signal SIGINT, Interrupt. | |
| 0xffffffff87fa0de4 in udelay (usec=<value optimized out>) at time.c:78 | |
| 78 while ((tmo - read_c0_count()) < 0x7fffffff) |