I don't know what's the added value of the test I've just done, but let
me share anyway.
Beside FreeDOS session in VirtualBOX I've also a MS-DOS 6.22 session so
I've done the same test in both sessions - maybe it helps to isolate the
problem.
First of all I've created in Linux 2 identical IMG files with the
command "mkfs.msdos -C disk.img 720" (disk1.img and disk2.img); one to
be used with FreeDOS and one with MS-DOS.
Then in FreeDOS:
1) started the session
2) attached disk1.img as A:
3) from C: I run "chkdsk a:" --> no problems found, here below the output
ChkDsk beta 0.9.2
Copyright 2002, 2003, 2009 Imre Leber under the GNU GPL
Elapsed time: 0s
The disk serial number is 64A8-C4EB
730.112 bytes total drive size
0 bytes in a total of 0 files
0 bytes in 0 directories
0 total size of files
730.112 bytes available on the volume
1.024 bytes in every cluster
713 total number of clusters
713 number of free clusters
4) A:
5) from A: I run "dir > dir.txt"
6) from A: I run "type dir.txt" that returned an unexpected content as
following:
\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00
730,112 bytes free
7) C:
8) from C: I run "chkdsk a:" --> "dos.txt" file containing free clusters
as below:
ChkDsk beta 0.9.2
Copyright 2002, 2003, 2009 Imre Leber under the GNU GPL
\DIR.TXT contains a free cluster
Errors were found. You did not use the /F switch. Errors are not corrected
Elapsed time: 0s
The disk serial number is 7317-8D86
730.112 bytes total drive size
1.024 bytes in a total of 1 files
0 bytes in 0 directories
224 total size of files
730.112 bytes available on the volume
1.024 bytes in every cluster
713 total number of clusters
713 number of free clusters
Then in MS-DOS 6.22:
1) started the session
2) attached disk2.img as A:
3) from C: I run "chkdsk a:" --> no problems found, here below the output
Volume Serial Number is CF38-00D8
730.112 bytes total disk space
730.112 bytes available on disk
1.024 bytes in each allocation unit
713 total allocation units on disk
713 available allocation units on disk
655.360 total bytes memory
566.208 bytes free
Instead of using CHKDSK, try using SCANDISK. SCANDISK can reliably detect
and fix a much wider range of disk problems. For more information,
type HELP SCANDISK from the command prompt.
4) A:
5) from A: I run "dir > dir.txt"
6) from A: I run "type dir.txt" that returned something that seems
expected but actually is not, the size of "dir.txt" is 0 bytes - I
didn't notice this in the beginning:
Volume in drive A has no label
Volume Serial Number is CF38-00D8
Directory of A:\
DIR TXT 0 13/11/24 18.10
1 file(s) 0 bytes
729.088 bytes free
7) C:
8) from C: I run "chkdsk a:" --> apparently seems ok,
Volume Serial Number is CF38-00D8
730.112 bytes total disk space
1.024 bytes in 1 user files
729.088 bytes available on disk
1.024 bytes in each allocation unit
713 total allocation units on disk
712 available allocation units on disk
655.360 total bytes memory
566.208 bytes free
Instead of using CHKDSK, try using SCANDISK. SCANDISK can reliably detect
and fix a much wider range of disk problems. For more information,
type HELP SCANDISK from the command prompt.
9) Quit MS-DOS session
Then after noticed the 0 byte size for the "dos.txt" file:
10) I've restarted the MS-DOS session to check again the "dir.txt" file
in A: and now, but I don't since when, it's size is 222 bytes.
I don't know exactly what to conclude, maybe that, in different ways,
both FreeDOS and MS-DOS have issues with diskette IMG files in
VirtualBOX ? or VirtualBOX iteself has something wrong in managing IMG
files ?
NB: Thanks to all for the advices (logger, guestmount, etc.).
Il 13/11/24 17:49, Paul Dufresne via Freedos-user ha scritto:
---- Le mer., 13 nov. 2024 07:05:32 -0500 Jim Hall via Freedos-user a écrit
----
>
>
> On Tue, Nov 12, 2024, 9:54 PM Paul Dufresne via Freedos-user
freedos-user@lists.sourceforge.net> wrote:
> Basically... there seems to be some corruption of the A: filesystem.
>
> Sometime I open test2 directory... and the dir shows meaningless
characters and big size.
>
> Sometime wcl testcol.c have:
> Run chkdsk: Bad FAT value: 0x00000000
> [..]
>
>
> Well, that's worrisome if there's sometimes floppy corruption. Now the
question is: what's causing it. Source could be from the virtual machine or the
kernel.
>
> I guess I'll have to start doing my work from a virtual floppy and see if I
can experience the same problems in QEMU.
>
> I'll take this as an excuse to experiment with writing a game I've been
thinking of. You throw the first version away, anyway— so I guess it's not a big
deal if I lose my work. :-)
>
> Sounds like you find the issue before too long on VirtualBox. If I can't
reproduce the problem on QEMU with a virtual floppy, after several hours of work,
then I'd look suspiciously towards VirtualBox.
>
I have tried to reproduce this in QEMU for about 20 mins... but was not able.
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