Bart Oldeman wrote:
> 2009/8/6 Christian Masloch <c...@bttr-software.de>:
>   
>> the kernel is supposed to support all Int21.7304 (Set DPB/BPB fields for
>> formatting) subfunctions but doesn't provide subfunction 03h completely.
>> The current code simply gets (and sets as requested) the flags from the
>> BPB, but doesn't move the FAT accordingly. MS-DOS apparently contains code
>> to do so. This isn't documented in RBIL, but can be tested by setting the
>> active FAT (of a FAT32 drive) to a single one, then resetting the flags to
>> include all FATs later. The second call overwrites the previously inactive
>> FAT(s) with a copy of the active one. (Depending on the size of the file
>> system, this results in a short delay. If this isn't the case,
>> files/directories can be created (changing FAT entries) while only the
>> active FAT is used and dosfsck can be used to insure both FATs have the
>> same content later when the flags were reset.)
>>     
>
> About a month ago I looked at the int21/ah=73 functions and there are
> a lot of corrections to make, mostly because RBIL is very brief in
> this area.
>
> I found this documentation which says more or less what you tell us too:
> http://www.thehackademy.net/madchat/vxdevl/vxmags/moonbug05/FAT32_32.HTM
>   

Yeah, the RBIL was mainly used as guide for development of FAT32 support, but 
MSDN was checked too, though RBIL was more complete on this topic at that time, 
dunno about MSDN's completeness at present time. We really need more complete 
docs on FAT32 to support it smoothly. Various bits of the info are spread over 
the internet here and there. Recovering the truth from these bits are very 
painful process.

Victor Vlasenko


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