Re: [Freedos-devel] The block device driver interface

Hi all, Tom pointed out some important limitation of all interfaces: No matter what you do, DOS interfaces still do NOT support handling of files above 4 GB in size. Even if you use the network redirector interface. A normal DOS app can only access the first 4 GB of a file, or at least it can not

Re: [Freedos-devel] The block device driver interface

Hi guys, A normal DOS app can only access the first 4 GB of a file, or at least it can not seek beyond that, nor can it know about file sizes being beyond that. This came to my mind, too! Where is INT 21h, AX=7142h, the LFN/extended/DOS7+ equivalent of seeking in a file? It could be

Re: [Freedos-devel] The block device driver interface

On Oct 9, 2015 10:36 AM, "Joe Forster/STA" wrote: > > Hi guys, > > >> A normal DOS app can only access the first 4 GB of a file, or at least it can not seek beyond that, nor can it know about file sizes being beyond that. > > > This came to my mind, too! Where is INT 21h,

Re: [Freedos-devel] The block device driver interface

> Any foreign filesystem driver for a modern is (e.g. ext# ...) > should optionally include support for LFN api.  Note that EDR kernel > includes extended LFN api for seeking in greater than 4GB files.  > Assuming a program doesn't seek, INT 2F CU - NETWORK REDIRECTOR - READ FROM REMOTE FILE

Re: [Freedos-devel] The block device driver interface

> In the book Adams/Tondo "Writing DOS device drivers in C" they describe a > WORM 3363 device driver that tells DOS that it accesses a 32 MB FAT disk. > The driver then maps these 32 MB to the 200 MB WORM drive. If DOS tries to > write to the emulated 32 MB FAT disk, once the 32 MB are used up,

Re: [Freedos-devel] The block device driver interface

Hi Eric, I would go for your third alternative and try to map e.g. an ext2 formatted disk to a FAT32 disk for DOS. This has some problems which you can observe with the utilities which make an ext2 disk available for Windows. It could be done within a single block device driver and you could

Re: [Freedos-devel] The block device driver interface

I want to second Bret and point out that MS-DOS supports to write a block device driver that allows DOS to access a non-FAT disk. Let me cite a few explanations in books I have: Ray Duncan writes in "Advanced DOS 2nd edition" page 261f: "Given adequate information about the hardware, any

Re: [Freedos-devel] The block device driver interface

Hi Georg, thanks for your detailed explanations of Bret's point! > So again, the block device driver interface is not limited to FAT disks. Correct, but non-FAT devices, be it raw BIOS or supported by a block device driver, do not directly allow DOS to do things with the files on those

Re: [Freedos-devel] The block device driver interface

Hi Georg, > I would go for your third alternative and try to map e.g. an ext2 formatted > disk to a FAT32 disk for DOS. This has some problems which you can observe > with the utilities which make an ext2 disk available for Windows. It could > be done within a single block device driver and