How to patch FAT32 boot sector External links Options

[ktp]

Well, there were so many reformats of the device after my many experimentations, each time I have to reload everything, redo all my mp3 player many settings, reupload my mp3 files, so I am really tired of it. And the last straw was the last experimentation patching mkbootfat MBR, it hang TinyHexer so strongly that even explorer.exe hangs, no way to use the taskbar, just Ctrl-Tab. I tried to unplug by force without success. I have to reboot. It was enough for me, at least for today :-).

[dencorso]

Here :
http://www.911cd.net/forums//index.php?sho...1702&st=129

For what it's worth, here I offer the boot-land community my revised version of Clemens Fruhwirth's KillCHS utility, both compiled and as source code, alongside with Fruhwirth's original code renamed killchs.ori, to help those interested in determining what I added to the code. My revised version can patch the NTFS boot loader and both flavors of the FAT-32 NTLDR boot loader (viz. MSWIN4.1 and MSDOS5.0). It has been compiled with djgpp's gcc 4.10 and runs in the NT-family Windows OSes, in Win 9x/ME and in plain DOS (but CWSDPMI is required).
Usage is simple:
KillCHS <filename.ext>
It will crash, however, if run without providing a filename.
Update (Aug 01, 2009): I've incorporated Icecube's suggestions (in post #24, below) and revised further the code. The new version (1.2) is more user-friendly, and only accepts one parameter, but it'll just complain and do nothing in case none or more are provided in the command line, instead of crashing on none and ignoring all parameters but the first, when more than one is provided.

Attached File(s)

 KillCHS.7z ( 34.59K ) Number of downloads: 194

 

[was_jaclaz]

It was enough for me, at least for today :-).

Yesterday was already tomorrow.

Anyway I re-thought a bit about the matter:

Of course, it depends on the actual checks the "stupid" MP3 thingy does, if for example it wants the number of "hidden sectors" to be equal to 0, we need to manipulate the data about "reserved sectors" or invent something else.

On a "normal" "superfloppy":
The number of hidden sectors is 0 (zero) as the bootsector is first sector of the disk.
The number of reserved sectors is determined by size of volume and app that formatted it

i.e. in Tiny Hexer "Structure Viewer" (example):

CODE

...
Reserved Sectors:              '0x0020' (32 dec)
...
Hidden sectors:                '0x00000000' (0 dec)
...

On a partitioned drive with 63 hidden sectors the values in the "right" bootsector (the one on sector 63 LBA) are, again in Tiny Hexer:

CODE

...
Reserved Sectors:              '0x0024' (36 dec)
...
Hidden sectors:                '0x0000003F' (63 dec)
...

We copied this latter values on the "fake" bootsector DATA on first sector of disk, and they are actually "wrong", there.

You should try incrementing the "Reserved Sectors" and decrement the "Hidden Sectors" by the offset we created, i.e. 63 or 0x3F.

Thus you will have:

CODE

...
Reserved Sectors:              '0x0063' (99 dec)
...
Hidden sectors:                '0x00000000' (0 dec)
...

When you will feel tomorrow has come, that would be the try to make.

@dencorso
Thanks for the app.
I cross-posted it on original thread:
http://www.911cd.net/forums//index.php?sho...1702&st=241



jaclaz

[Icecube]

@dencorso
The following code will check if a argv1 exists before continuing.
Also added some more info about what the program does (maybe not complete. I didn't read the topic very carefully).

CODE

int main(int argc, char **argv) {

    printf("\nKillCHS, by Clemens Fruhwirth <clemens@endorphin.org>, 2007.\n\
(revised by dencorso, 2009).\n\n \
   This program binary patches the FAT32/NTFS boot loader to never ever\n \
   use CHS based indexing again. CHS based access is broken when then\n \
   disk geometry for heads and sectors is different from the one\n \
   stored in the BPB.\n\n");

    if(argc < 2) {
        perror("Usage: killchs <file>\n"); return 1;
    }

    int fd=open(argv[1],O_RDWR|O_BINARY);
    unsigned char buf[512];

Side note: The source code is also not consistently formatted.

[wimb]

@ktp

To make it bootable you need also:

FAT32 Bootsector - drive-id patch 0x80 at offset 0x40 , after XP format it is 00 and Not bootable

http://www.boot-land.net/forums/index.php?...5306&st=214

More Info on BootSector patches in Format Stick Section of improved Tutorial
http://www.boot-land.net/forums/index.php?showtopic=5306

[dencorso]

I cross-posted it on original thread:
http://www.911cd.net/forums//index.php?sho...1702&st=241

Thanks, jaclaz! I have updated the KillCHS program to v. 1.2, by incorporating Icecube's suggestions (thanks, Icecube!), and revising a little more the whole code. The new version is now in place of the former, still in post #22, so that your posted link remains valid. You both rock!
Side note: The source code remains not consistently formatted, but is nevetheless, a little better, visually.

[online]

@ktp
Not sure if the patching at every boot-up could be useful in your case...
Please, see here
http://www.boot-land.net/forums/index.php?...ost&p=73826