China DOS Union

After looking at the isolinux code, I feel that booting from CD still needs a lot of patch code aimed at buggy BIOSes. Right now the bit of code in the grldr header is too small, and there is no room to add new code.

So, a natural idea is to write a boot sector specifically for CD, just like the grldr.mbr we wrote for the hard disk.

The CD boot sector we write should be exactly one CD sector in length (2048 bytes). It is a no-emulation mode boot file. After the BIOS passes control to it, it will then look in the root directory of the CD for the grldr file and boot it.

So what should this 2048-byte file be called? Please give your opinions.

Some people have suggested the following names:

grcd.bin

grldr.cd

cdgrub.bin

isogrub.bin

But I feel they may still not be ideal, or rather they all have drawbacks. For example, names ending in .bin have too many meanings. In CD booting, a .bin file usually refers to a file searched for and loaded by a boot sector. For example setupldr.bin, isolinux.bin, and so on.

A file ending in .cd has also been used before as the name of an entire CD image (meaning the same as .iso), so .cd is not very ideal either.

I also gave it some thought and came up with .nbr, meaning no-emulation boot record. It differs from .mbr by only one letter, and the whole file would be called grldr.nbr.

Please see if there are any better names and keep them coming. Thanks.

Then call it CD.NBR

Or grldr.cdrom

grldr.bootcd

grldr.cd-boot

grldr.cdbr ( cd boot record )


nbr easily makes people think of net boot

BIN is the extension for Microsoft binary files
cdgrub.rom
isogrub.rom
seem more suitable for grub



Been lurking for a long time, but after seeing this I still have to bump it

Originally posted by fastslz at 2007-10-9 22:18:
BIN is the extension for Microsoft binary files
cdgrub.rom
isogrub.rom
seem more suitable for grub



Been lurking for a long time, but after seeing this I still have to bump it :P

Very similar to what I think too

isogrub then... ;)


syslinux also uses a bin file, isolinux.bin, and everyone recognizes syslinux quite highly; almost all Linux CDs use isolinux

If it uses the signature name grldr, that would be good too

[ Last edited by barton on 2007-10-10 at 08:58 AM ]

Thanks. And special thanks for this line:

nbr easily makes people think of net boot

I hadn't thought of that.

According to the plan, our CD boot sector will look for the grldr file in the root directory of the CD (and if possible, also in some subdirectory). Therefore, following the naming method of grldr.mbr searching for grldr on the hard disk, our CD boot sector should also use grldr as the base name, with a suffix (extension) added after it.

The suffix .cdbr is also fairly good (I checked online, and it does not duplicate any existing name), except that it is more than 3 letters.

I also checked the following: br, cbr (c stands for cd), obr (o stands for optical disc, that is CD), cdb, cdr, and so on. They all have other meanings, and those extensions are already used by other software. Go here: http://file-extension.net/seeker/ and it becomes clear with one search.

Thinking about it now, although nbr may at first make people think of net boot record, after all nobody has seen such a thing as a "net boot record" yet, so it is still a usable name.


Just now I specifically looked up information on obr again:
http://file-extension.net/seeker/filename_extension_obr

It has the following meanings:
FILExt OBR C++ Object Browser Data File (Borland Software Corporation)
Wikipedia OBR Object browser data file - Borland C
FILExt OBR Objective Reference Document Link (Objective Corporation Limited)

This shows that although it conflicts somewhat with Borland and so on, the conflict is not very serious (the overlap is narrow, limited to programming languages, and the companies behind such languages are gradually fading from the market now).

There are two advantages to using obr: first, o means optical disc; second, the letter o is round and especially looks like a CD.

Please keep suggesting more.

[ Last edited by 不点 on 2007-10-10 at 11:55 AM ]

My feeling is that there probably aren't many people who, on seeing o, would think of optical :(

Even when they see an optical drive, even when the name itself contains "optical," there probably aren't many who know it uses optical principles :)

On the contrary, terms like cd, vcd, dvd are deeply rooted in people's minds. Even people who know absolutely nothing about computers have probably heard of CD

So I think the extension should contain cd

What is the problem with exceeding 3 letters??

Now let's treat those within three letters and those over three letters separately.

Normally, we choose something no more than three letters, but if it really is not easy to find a suitable combination in three letters, then more letters can also be considered. With more letters there is no limit on the number of letters, so the range of choices is very wide. Therefore, we should mainly consider combinations of three letters or fewer.

Why limit it to three letters? Because a three-letter extension is a so-called "de facto industry standard." In the early days DOS could only accept three-letter extensions, and later that even influenced the formulation of the CDROM standard. In the iso9660 standard, the basic filename is in 8.3 format, exactly the same as DOS, which cannot but be said to have been influenced by DOS. Important Microsoft system files all conform to the 8.3 format. For example, bootmgr, ntldr, setupldr.bin, and so on.

For now let's nominate names. If we really cannot decide later, we'll have a vote.

-----------

Two more nominations:

bcd ---- bootable cd
noe ---- no emulation

Among them, bcd can be seen on Gujin's homepage http://gujin.sourceforge.net/ where there is the following code fragment:

./instboot boot.bin boot.bcd --full # For Bootable CD in no emulation mode, use with "mkisofs -no-emul-boot -boot-load-size 4 -b boot.bcd"

The boot.bcd above is the no-emu CD boot sector.

[ Last edited by 不点 on 2007-10-10 at 03:26 PM ]

It seems Vista has a bcd too (Boot Configuration Data), would that cause confusion

Actually, this file does not exist on the CD as a file, but is written into the boot sector,

and making a bootable CD image is usually done under win or linux,

so the DOS and iso9660 8.3 standard should not be a problem

Although noe is not very fitting either, I rather like it, because if you switch the order it becomes neo (the male lead in The Matrix) :)

Actually, this file does not exist on the CD as a file, but is written into the boot sector,

It may exist as a file on a CD or disk. When we release it, won't we release it in file form? Otherwise how would people "make a CD"?

Besides, like grldr.mbr, this boot sector is a general-purpose boot sector. As long as GRLDR inside it is replaced with another name, it can boot some other file. So an external program can absolutely call this boot sector to boot a file other than grldr.

That is to say, this boot sector does not have to exist as the "main boot sector" on a CD; it can exist as an ordinary file. The "main boot sector" on the CD can entirely be some other software, for example the boot sector of ISOLINUX. When ISOLINUX calls our boot file, it can boot the GRLDR file on the CD. So our boot file absolutely must have a proper name!

Oh... makes sense

If this is implemented in the future, say it is called grldr.nbr, then it is very likely other software will also make similar files, such as grldr1.nbr, grldr2.nbr, and so on. Then the suffix nbr may become a kind of "standard," implying this is the grldr.nbr format. Therefore, the "uniqueness" of the extension is very important; if it has another meaning, then it is not very ideal.

At present, those that satisfy this strict condition of "uniqueness" are really hard to find. Probably only the following two are possible:

nbr
noe

cdshell ----------->loader.bin
bcdw-------------->loader.bin



all are loader.bin



or



grldr.mkb----------》 make bootable cd

File extension .MKB is not in any of the databases.
http://filext.com/file-extension/mkb