Hi Alain, > > - the FAT12 / FAT16 boot sectors are too stuffed to > > check int13.8 for real geometry, but we could say > > that LBA is often supported - then we get to my > > suggestion "allow LBA even for A: if FAT16"... :-). > > When you use LBA, wrong CHS geometry is irrelevant. > > There are always people running FreeDOS on old machines, > wouldn't this create a problem?
Only if the old machine reports to support LBA while in reality the LBA is broken. This seems to be the case for old BIOS cdrom boot floppy emu as far as I understand a comment in the source code. Which is why I suggest to re-allow LBA even for LBA for FAT16 but keep it blocked for FAT12... Our FAT12 and FAT16 boot sectors check if LBA is supported at boot time and will not try to use LBA if it is not supported :-). > Another comment: SYS makes some runtime decisions about BIOS, > would that be a problem if I change the disk physicaly to > another machine? IN which situations could a problem happen? Yes! The FAT12 and FAT16 boot sectors decide whether they can use LBA at runtime, but for FAT32, SYS decides when you SYS a drive. If drive 0x80 (first harddisk) is LBA accessible then, SYS will use LBA boot sectors for all(!) harddisks. If not, it will use CHS boot sectors for all the harddisks... This has two problems: - SYS with FAT32 CHS and boot on another LBA enabled PC later: the other PC could use another geometry for the disk, no boot Variant: Drive 0x80 has no LBA but you SYS another drive where you do have and even need (cyl>1024) LBA, no boot either... - SYS with FAT32 LBA and boot on another LBA unable PC later: cannot boot because there is no LBA to use (plus LBA is 386+) Variant: Drive 0x80 has LBA but you SYS another drive where you have no LBA - you would have to move the drive to a PC or controller where you do have LBA to be able to boot it... ... I suggest to add a command line option to manually pick either CHS or LBA for FAT32 and override the default. Such an option could conceivably also affect FAT12 / FAT16, but the LBA detection at boot time for FAT12 / FAT16 looks ok. Suggestions for the syntax of such an option? How should it treat FAT12 / FAT16, show a message "ignored choice" maybe? Eric ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
