IMGMAKE VHD support not working as expected/documented

[Jroonk]

Not sure where to report this, so I figured here is as good a place as any. There is either bugs with the VHD support in IMGMAKE, problems with the wiki site that need to be updated, or both. See my steps below before I got something working.

I downloaded the latest release as of this writing: dosbox-x-vsbuild-win64-20231007055223, running in a Windows 11 (64 bit) host. And I've used IMG disk images successfully for a while, but I was trying to test dynamic VHDs. I'm trying to follow the instructions found here: https://dosbox-x.com/wiki/Guide%3AManaging-image-files-in-DOSBox%E2%80%90X#_vhd_support

From that site, typing the command as written doesn't work:
Z:\>imgmake hdd.vhd -type vhd -size 2097152
It doesn't work because the "-type" parameter is invalid. The type is specified with a "-t".

So changing that:
Z:\>imgmake hdd.vhd -t vhd -size 2097152
Wrong -size or -chs arguments

Wondering if it may be something that is too close to the 2GB limit, I tried 1GB (1048576) and that worked fine. So then I tried 2000000, and that worked fine, and from there I just played the pick the next highest digit until I found that the max allowable size was 2088960:
Z:\>imgmake hdd.vhd -t vhd -size 2088960
Creating image file "hdd.vhd" with 65535 cylinders, 16 heads and 255 sectors
(Side note... is anyone else annoyed by the lack of the oxford comma in the response?)

Once I got valid VHD files, I had no trouble mounting them, per the posted instructions.

[rderooy]

I noticed the "-type" issue on the wiki last year, and fixed it for the next update of the docs, which is pending on the next DOSBox-X release.

[Jroonk]

Any thoughts on size? Seems more like imgmake bug? Because 2097152 is the correct value for 2gb.

[rderooy]

Yes, but from a DOSBox perspective "65536 cylinders, 16 heads and 255 sectors" is the maximum supported using CHS addressing. Anything beyond that needs to use LBA addressing instead.

Such large disks were a big issue in the first half of the 90's. It required a new BIOS to be able to boot from such disks, and updates to operating systems.

Still that presumably should not prevent imgmake from creating such files, because obviously VHD files can be much larger.

[Torinde]

The size value is in MegaBytes - see IMGMAKE help: -size: Size of a custom hard disk image in MB (vhd: up to 2088960).

So, that's the maximum possible for VHD ~2TB (not 2GB).