> You could write such a driver but you have to remember that "DOS
> block device" already implies FAT anyway.

This implication is a part of the problem I'm talking about. DOS (rather,  
the DOS device loader) shouldn't assume that just FAT exists (it also  
shouldn't discard non-FAT partitions from the MBR) but instead it should  
first provide any filesystem to all loaded redirectors so if one of the  
redirectors finds a non-FAT partition with a supported filesystem it could  
add this block device to it's devices.

> In the ATAPI CD/DVD case, that interface is some
> int2f and some "DOS character device" interface, nothing "block".

Why do CD/DVD drivers need to have a DOS device visible to the DOS kernel  
at all, then? Actually, they don't. Pretending that it's a character  
device (which CD-ROMs usually aren't) is a hack (probably to save some  
memory compared to dumb PSP TSRs). If MS-DOS (3.x) had support for linking  
the redirector interface with block devices, CD/DVD drivers would probably  
be written as DOS block devices, reporting impossible values when asked  
for a (FAT-specific) BPB. (This won't require reading the CD-ROM.) The  
*CDEX redirector would then search unhandled block devices and provide  
access to those that access some sort of CDFS. A NTFS redirector would  
just search unhandled block devices for a device that accesses NTFS,  
instead of CDFS.

The major problem seems that the redirector interface was designed for  
network redirectors, not for any kind of local non-FAT filesystem driver.


This SF.net email is sponsored by:
SourcForge Community
SourceForge wants to tell your story.
Freedos-user mailing list

Reply via email to