FreeDOS/docs/relnotes.txt

Release notes for kernel 2024d and its development predecessors
2024BL,M,N: we think that by now we have ironed out most of these
bugs, but be careful nonetheless.

About KE2024BL:

    *********************************************************
    *                                                       *
    *      THIS IS A BETA RELEASE                           *
    *                                                       *
    *             BE CAREFUL                                *
    *                                                       *
    *           SAVE YOUR DATA. SAVE OFTEN.                 *
    *                                                       *
    * THIS RELEASE MAY DESTROY YOUR DISK COMPLETELY         *
    *                                                       *
    *********************************************************


KE2024BL introduced full LBA support; i.e. disk may be up to 
2^32 * 512 bytes = 2000 GB large. 

also new is the working of 64K FAT clustersize for a max 
logical disksize of 2^16 * 64K = ~4 GB.

KE2024BM is its follower, with some more bugfixes.


How dangerous is it?

The KE2024BL kernel has been send by private mail to some of us,
has been tested on 7 maschines with and without LBA support.

No errors (other then the known bugs) were reported.
And KE2024BM is pretty conservativ, before it accepts and uses
a disk.

the main problem may be, that a disk recognized by an older
kernel, will no longer work with the new one, because strange
partitioning scemes, although nothing like that has been reported.

So, if after booting you see all your drives, containing resonable 
data, it should be pretty save to use.

Be a bit careful, nevertheless.






full LBA support and 64K FAT clustersize for a max 
logical disksize of 2^16 * 64K = ~4 GB 


were have been tested in the following way:

on my 30GB disk, a partition with 1.7 GB for 32K clusters and
3.5 GB for 64K clusters created. the 3.5 GB partition was created,
using Win2K.

my WINNT directory (~350MB) was copied there - (using VC)
once for 32K,
for 64K,
    xcopy c:\WINNT j:\WINNT /s
    xcopy j:\WINNT j:\WINN1 /s
    xcopy j:\WINN1 j:\WINN2 /s
    xcopy j:\WINN2 j:\WINN3 /s
    xcopy j:\WINN3 j:\WINN4 /s
to fill the disk.


the 350 MB files (WINNT for 32K, WINN4 for 64K) were then 
compared to the original file. they were identical.

no, not all files were copied due to restrictions in MAX_PATH_SIZE,
but the files, that were copied, compared ok.

the files were also readable with WinNT, and they were identical, too.
WinNT chkdsk was content with the disk.


next, the kernel source was copied to this drive, compiled,
and verified.

so, it _seems_ to work for me.

known issues:
  * VC will say, that the disk has size of 0 byte, with 0 byte free.
    this is not a kernel bug. 
    VC simply multiplies BytesPerSec*SecPerCluster, gets 
    128*512 = 0x10000, and saves the low part, which is 0.

  * the behaviour for filesize at or above 2GB (where the sign 
    gets negative) is completely untested. test it, if you like    

  * there are some bugs, when the pathlength is around 64.
    this may lead to incontinent (sorry, inconsistent) behaviour,
    like
        you can MKDIR a directory, but not CHDIR to it
    and similiar things.
    some of them found and removed, but there are probably more
    to be found yet. fortunately, none lead to data loss :-)


    *********************************************************
    *                                                       *
    *       BE CAREFUL                                      *
    * AND SAVE YOUR DATA. SAVE OFTEN.                       *
    *                                                       *
    *********************************************************


Bugs and fixes in the FAT filesystem (tested on KE2024BN)

---------------------------------------------------------
KE2024BM:
Disk Full not detected in a compatible way.
it was possible to create a directory(pointing to nowhere),
even if disk was full.

---------------------------------------------------------
DosGetFreeSpace is wrong (verified on KE2022, too):

when creating files, the 2nd and following clusters are 
counted twice when created.

simply copy one file to another, delete 2nd file;
watch free space before and after. 
corrected in KE2024BP

---------------------------------------------------------
#include <stdio.h>
#include <io.h>
main()
{
	FILE *fd = fopen("test.dat","w");
	int fdn = fileno(fd);

	lseek(fdn,10000,SEEK_CUR);
	write(fdn,"hello world",10);
}

creates file of DirSize 10010 bytes, but reserves 
a single FAT entry cluster

this is obviously nonsense.

and there is no "hello world" in it :-(

cured by FATFS.C, 
  /* Now that we've found a free FAT entry, mark it as the last   */
  /* entry and save it.                                           */
  /* BUG!! this caused wrong allocation, if file was created, 
     then seeked, then written */
+  fnp->f_cluster = 
        fnp->f_dir.dir_start = free_fat;




--------------------------------------------------------------
when a big file is created, and cut afterward, the filespace is NOT freed
try:
    copy command.com xx
    dir
    echo >xx
    dir
and compare disk free info.
the space is freed, however, if xx is deleted after that.
--------------------------------------------------------------    




regards
tom ehlert (tom.ehlert@ginko.de)