6 replies to this topic

[steve6375]

[Edit] This is NOT a bug in grub4dos!!! It is a bug in RMPrepUSB FAT32 formatting! Now fixed in v2.1.661.[/Edit]

 

I have a few USB pens formatted as FAT32 and I often place ISO files in the root just to quickly test them. Suddenly I found that grub4dos would not list some files that I just added on one of them! The new files are there in Windows Explorer but not under grub4dos. Even if I deleted some files from the root and then added a new file to the root again it was not listed.

 

I have noticed peculiar issues like this in the past and had to reformat the USB drive to fix it. 

 

I have reported this as a bug here.

 

To demonstrate this try making a new FAT32 USB flash drive with RMPrepUSB - installing grub4dos and then run this .cmd file from your Windows console

 

set USB=H:
set a=0

:LOOP
set /a a=a+1
echo t > %USB%\%a%.txt
if "%a%"=="130" goto :P
goto :LOOP

:P
del %USB%\126.txt
del %USB%\125.txt
del %USB%\124.txt
copy %USB%\1.txt %USB%\NEW1.txt
copy %USB%\2.txt %USB%\NEW2.txt
copy %USB%\3.txt %USB%\NEW3.txt

 

Now boot to grub4dos and do  ls /     - you should see that the NEWx.txt files are not listed, nor are any files above 126.txt!

 

If you often add/delete files from the root of a grub4dos FAT32 drive, you may find a similar issue.

 

Can someone confirm this bug please?

[steve6375]

Just tested FAT16 and it seems OK in FAT16!

[steve6375]

Interesting - if I re-format using Windows FAT32, then the problem does not arise.????

I wonder why???

[Wonko the Sane]

Interesting - if I re-format using Windows FAT32, then the problem does not arise.????

I wonder why???

Somehow it means that the RMPREPUSB USB formatting is *somehow* different from the built-in Windows one (BTW which Windows? Though I don't think there are differences in FAT32).

 

Could it be related to the "optimization" offsets?

 

Wonko

[steve6375]

An old version of RMPrepUSB (1.9.75) has the same issue.

I changed the partition type from C (RMprepUSB) to B (win) and still same issue.

I changed text in PBR from MSDOS 5.1  (rmprepusb) to 5.0 (win) still same issue.

Attached Files

•  RMPREP_USBInfo.Txt   6.45KB   651 downloads
•  Win_USBInfo.Txt   6.1KB   655 downloads

[steve6375]

must be long-standing bug in RMprepUSB FAT32 procedure - I will work on it!

[steve6375]

 After making the BPB parameters and sectors 1-3 of the PBR identical the still occurred!

Clearly the issue was after the BPB.

I eventually traced it to the first 3 cluster entries!!

 

On a volume formatted by Windows these were:

F8 FF FF 0F    FF FF FF 0F   FF FF FF 0F

on an RMPrepUSB formatted volume they were:

F8 FF FF FF   FF FF FF FF   FF FF FF FF

 

this apparently caused the problem!!??

 

This now fixed in 2.1.661 which will be available shortly!