question about boot sector

[taxus]

Hello everyone,now I'm trying to write a boot sector
I had read some documents
What bother me is whether the boot sector must have a function to locate where is the loader.bin
I don't know where to find a good tutorial about boot sector,thanks for give me some advise

PS.Is the boot sector always means dos boot sector?

[Chandra]

Google.

[bluemoon]

Hello everyone,now I'm trying to write a boot sector

To program a boot sector, check the wiki resources below.
To write a boot sector using dd

Code: Select all

dd if=boot0.bin of=(partition) bs=1 skip=0 seek=0 count=512 conv=notrunc

I had read some documents. What bother me is whether the boot sector must have a function to locate where is the loader.bin

No it's not a must, a boot sector may load code from anywhere, or execute random instructions, or just hang.

I don't know where to find a good tutorial about boot sector,thanks for give me some advise
PS.Is the boot sector always means dos boot sector?

Did you check the wiki? 3 hits on the same site.

• Boot_sequence

• Rolling_Your_Own_Bootloader

• Bootloader

PS. boot sector always means boot sector.

[taxus]

Hello everyone,now I'm trying to write a boot sector

To program a boot sector, check the wiki resources below.
To write a boot sector using dd

Code: Select all

dd if=boot0.bin of=(partition) bs=1 skip=0 seek=0 count=512 conv=notrunc

I had read some documents. What bother me is whether the boot sector must have a function to locate where is the loader.bin

No it's not a must, a boot sector may load code from anywhere, or execute random instructions, or just hang.

I don't know where to find a good tutorial about boot sector,thanks for give me some advise
PS.Is the boot sector always means dos boot sector?

Did you check the wiki? 3 hits on the same site.

• Boot_sequence

• Rolling_Your_Own_Bootloader

• Bootloader

PS. boot sector always means boot sector.

Wow,quite thanks for that ,your answer give me a lot of help,thanks

[taxus]

Have you tried reading before writing?

What problems did you encounter with writing? There are no specifics. All I can advise is go read some more documentation.

yea,I had read three or four documents,but I just don't know whether the boot sector must find the loader.bin
that means,can the loader.bin in a static address that the boot sector don't need a function to find where it is?
and also the loader don't need a function to find where is the kernel,does it possible?

[bluemoon]

It's up to your design where to place your 2nd stage loader
Some common examples:

• * in a file in boot partition (which you need to understand the file system and code in limited space, less than 512 bytes)

• * pre-defined sectors. If you have your own FS, you may put things starting right after the boot sector

• * For FAT, the reserved area is safe to abuse, and is configurable for different size

• * Fetch from TFTP. Ok this is not so common.

However, I would strongly advice to put kernel image(s) into file as it can someday grow to megabytes.
It will be ugly to place it on special sectors, or have the user to reformat the disk just to upgrade a bigger kernel.

also the loader don't need a function to find where is the kernel,does it possible?

Yes, if you pre-calculate the sector number of 2nd stage loader (and kernel images) and put that information into the loader.

[taxus]

I'm so appreciate for your help
It works now,I used a function to find the loader
maybe later I will try to calculate the address before that