Bochs and a few questions

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joao_foscarini

Joined: 11 Jan 2005
Posts: 5

joao_foscarini 03 Apr 2005, 23:33

1) Anyone here use Bochs? I'm having trouble setting it up on Linux and help would be appreciated. Rolling Eyes

2) How do I write my boot loader to the sector 0x7C00 of the floopy? Any specific program?

3) Anyone know any decent ASM tutorial I could use to make my OS? (newbie)

Thanks in advance,

Joao

EDIT - Okay, I think I got it to work.. but...:

Quote:

Please choose one: [2] 5
00000000000i[ ] installing x module as the Bochs GUI
00000000000i[ ] Bochs x86 Emulator 2.2.pre2
00000000000i[ ] Build from CVS snapshot on March 25, 2005
00000000000i[ ] System configuration
00000000000i[ ] processors: 1
00000000000i[ ] A20 line support: yes
00000000000i[ ] APIC support: no
00000000000i[ ] CPU configuration
00000000000i[ ] level: 5
00000000000i[ ] fpu support: yes
00000000000i[ ] paging support: yes, tlb enabled: yes
00000000000i[ ] mmx support: yes
00000000000i[ ] sse support: no
00000000000i[ ] v8086 mode support: yes
00000000000i[ ] 3dnow! support: no
00000000000i[ ] PAE support: no
00000000000i[ ] PGE support: no
00000000000i[ ] PSE support: no
00000000000i[ ] x86-64 support: no
00000000000i[ ] SEP support: no
00000000000i[ ] Optimization configuration
00000000000i[ ] Guest2HostTLB support: no
00000000000i[ ] RepeatSpeedups support: no
00000000000i[ ] Icache support: no
00000000000i[ ] Host Asm support: yes
00000000000i[ ] Fast function calls: no
00000000000e[ ] No romimage to load. Is your bochsrc file loaded/valid ?
00000000000i[MEM0 ] allocated memory at 0xb5b2c008. after alignment, vector=0xb5b2d000
00000000000i[MEM0 ] 32.00MB
00000000000p[MEM0 ] >>PANIC<< ROM: System BIOS image undefined
00000000000i[SYS ] Last time is 0
00000000000i[ ] restoring default signal behavior
========================================================================
Bochs is exiting with the following message:
[MEM0 ] ROM: System BIOS image undefined
========================================================================
00000000000i[CTRL ] quit_sim called with exit code 1

03 Apr 2005, 23:33

roticv

Joined: 19 Jun 2003
Posts: 374
Location: Singapore

roticv 04 Apr 2005, 00:13

1) I think bochs is a horrible tool. lol

2) You write to the first sector of your floppy, but the bios will load your boot loader to the address 0x7c00h and start from there.

04 Apr 2005, 00:13

joao_foscarini

Joined: 11 Jan 2005
Posts: 5

joao_foscarini 04 Apr 2005, 00:20

roticv wrote:

1) I think bochs is a horrible tool. lol

2) You write to the first sector of your floppy, but the bios will load your boot loader to the address 0x7c00h and start from there.

Heh.. I prefer to use bochs then having to reboot my computer to test everything I do.

I know, but how do I write to the first sector of the floopy? is there any program for Linux to do it? I've done it before on Windows, but I don't remember what program I used...

04 Apr 2005, 00:20

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 04 Apr 2005, 01:09

Try this to copy the bootsector to the file (change the word 'bootsector' to the name of your bootsector file):

Code:

dd if=bootsector of=/dev/fd0

04 Apr 2005, 01:09

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 04 Apr 2005, 01:15

Quote:

00000000000e[ ] No romimage to load. Is your bochsrc file loaded/valid?

That implies that there's a problem with your bochsrc file. Maybe wrong paths to the bios.bin and vgabios.bin files.

04 Apr 2005, 01:15

joao_foscarini

Joined: 11 Jan 2005
Posts: 5

joao_foscarini 04 Apr 2005, 01:37

Thanks.

Uhh.. about that problem, I downloaded the source code and runned ./configure && make && make install. I use Ubuntu Linux.. I might as well download from the Synaptic Package Manager...

Okay. I just did... now when I run, I get

Quote:

00000000000i[ ] installing x module as the Bochs GUI
00000000000i[ ] Bochs x86 Emulator 2.2.pre2
00000000000i[ ] Build from CVS snapshot on March 25, 2005
00000000000i[ ] System configuration
00000000000i[ ] processors: 1
00000000000i[ ] A20 line support: yes
00000000000i[ ] APIC support: no
00000000000i[ ] CPU configuration
00000000000i[ ] level: 5
00000000000i[ ] fpu support: yes
00000000000i[ ] paging support: yes, tlb enabled: yes
00000000000i[ ] mmx support: yes
00000000000i[ ] sse support: no
00000000000i[ ] v8086 mode support: yes
00000000000i[ ] 3dnow! support: no
00000000000i[ ] PAE support: no
00000000000i[ ] PGE support: no
00000000000i[ ] PSE support: no
00000000000i[ ] x86-64 support: no
00000000000i[ ] SEP support: no
00000000000i[ ] Optimization configuration
00000000000i[ ] Guest2HostTLB support: no
00000000000i[ ] RepeatSpeedups support: no
00000000000i[ ] Icache support: no
00000000000i[ ] Host Asm support: yes
00000000000i[ ] Fast function calls: no
00000000000e[ ] No romimage to load. Is your bochsrc file loaded/valid ?
00000000000i[MEM0 ] allocated memory at 0xb5b2c008. after alignment, vector=0xb5b2d000
00000000000i[MEM0 ] 32.00MB
00000000000p[MEM0 ] >>PANIC<< ROM: System BIOS image undefined
00000000000i[SYS ] Last time is 0
00000000000i[ ] restoring default signal behavior
========================================================================
Bochs is exiting with the following message:
[MEM0 ] ROM: System BIOS image undefined
========================================================================
00000000000i[CTRL ] quit_sim called with exit code 1

How do I 'define' it?
and that error still there. Hmm...

my bochsrc file:

Quote:

config_interface: textconfig
display_library: sdl
romimage: file=/usr/share/bochs/BIOS-bochs-latest, address=0xf0000
megs: 32
vgaromimage: file=/usr/share/vgabios/vgabios.bin
floppya: 1_44=/dev/fd0, status=inserted
ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
ata1: enabled=0, ioaddr1=0x170, ioaddr2=0x370, irq=15
ata2: enabled=0, ioaddr1=0x1e8, ioaddr2=0x3e0, irq=11
ata3: enabled=0, ioaddr1=0x168, ioaddr2=0x360, irq=9
#ata0-master: type=disk, path="", mode=flat, cylinders=1024, heads=16, spt=63
ata0-slave: type=cdrom, path="/dev/cdrom", status=inserted

boot: cdrom

ips: 1000000
floppy_bootsig_check: disabled=0
log: /dev/stdout
panic: action=ask
error: action=report
info: action=report
debug: action=ignore
debugger_log: -
com1: enabled=1, dev=/dev/ttyS0
parport1: enabled=1, file="/dev/lp0"
sb16: midimode=1, midi=/dev/midi00, wavemode=1, wave=/dev/dsp, loglevel=2, log=/dev/stdout, dmatimer=600000
vga_update_interval: 300000
keyboard_serial_delay: 250
keyboard_paste_delay: 100000
floppy_command_delay: 500
mouse: enabled=1
private_colormap: enabled=0
#ne2k: ioaddr=0x240, irq=9, mac=b0:c4:20:00:00:00, ethmod=linux, ethdev=eth0
#keyboard_mapping: enabled=0, map=/usr/share/bochs/keymaps/x11-pc-de.map
#keyboard_type: mf
#user_shortcut: keys=ctrlaltdel
#magic_break: enabled=1
#cmosimage: cmos.img
#load32bitOSImage: os=nullkernel, path=../kernel.img, iolog=../vga_io.log
#load32bitOSImage: os=linux, path=../linux.img, iolog=../vga_io.log, initrd=../initrd.img
#i440fxsupport: enabled=1
usb1: enabled=1, ioaddr=0xFF80, irq=10
#text_snapshot_check: enable

I don't see any bios.bin decleared... hmm...

04 Apr 2005, 01:37

Endre

Joined: 29 Dec 2003
Posts: 215
Location: Budapest, Hungary

Endre 04 Apr 2005, 12:25

joao_foscarini wrote:

I don't see any bios.bin decleared... hmm...

That's the problem. You may look at /usr/local/share/..., since install path prefix is usually /usr/local by default. Bochs also has a little program (I don't remember its name now, and I'm not at home currently, but you will certainly find it) which makes an empty FD/HDD image file. You can copy (with dd) your bootsector program into it and have bochs boot from it. If you want to copy/delete files (other than bootsector) to/from this image file just mount it as loop device (man mount).

04 Apr 2005, 12:25

joao_foscarini

Joined: 11 Jan 2005
Posts: 5

joao_foscarini 05 Apr 2005, 20:32

Endre wrote:

joao_foscarini wrote:
I don't see any bios.bin decleared... hmm...

That's the problem. You may look at /usr/local/share/..., since install path prefix is usually /usr/local by default. Bochs also has a little program (I don't remember its name now, and I'm not at home currently, but you will certainly find it) which makes an empty FD/HDD image file. You can copy (with dd) your bootsector program into it and have bochs boot from it. If you want to copy/delete files (other than bootsector) to/from this image file just mount it as loop device (man mount).

Hmm...

What is the little program that does that? and how exactly do I copy my bootsector program into it?

05 Apr 2005, 20:32

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 06 Apr 2005, 22:46

Quote:

romimage: file=/usr/share/bochs/BIOS-bochs-latest, address=0xf0000

That would be the equivilent of bios.bin. On your system it's called BIOS-bochs-latest.

06 Apr 2005, 22:46

Endre

Joined: 29 Dec 2003
Posts: 215
Location: Budapest, Hungary

Endre 09 Apr 2005, 12:42

Quote:

What is the little program that does that? and how exactly do I copy my bootsector program into it?

Its name is bximage. It's an interactive and easy to use tool. With this program you can create, for example, a floppy image, that you can copy your bootsector program to (assumed your bootsector program is my_boot.bin and your floppy image file is floppy.img) as follows:

Code:

dd if=my_boot.bin of=floppy.img bs=512 conv=notrunc

Now you can mount it as a loop device:

Code:

mount floppy.img /mnt/floppy -t msdos -o loop

Now you see your floppy.img normally under /mnt/floppy (or where you've mounted it). That means that you can copy/delete files to/from it as I already mentioned. You have to set this floppy.img in your .bochsrc to make bochs to be able to boot from it. If your newly developed system seems to work correctly under bochs then you may want to make a "real" test. You have to copy the whole image file onto a floppy. You can do it also with dd:

Code:

dd if=floppy.img of=/dev/fd0 bs=512

...and reboot your machine from this floppy.

09 Apr 2005, 12:42

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