In the xp.iso image, I have WinVBlock integrated. Maybe there is a CDFS (USB) driver for WinXP that also needs to be integrated into the ISO or/and need also add USB driver to [BootBusExtenders.Load] section in TXTSETUP.SIF file ???
WinVBlock, Imdisk are drivers at device level, before file systems.
There is cdfs.sys included by default.
cdfs = cdfs.sys
However this default udfs.sys seems to support CD/DVD devices like devices only, no (USB) mass storage devices.
There is a Matsushita DVD-RAM driver meiudfs.sys. As far as I rememver, not tested at (USB) mass storage devices.
There is a BartPE plugin using registry ControlSet001\Services\meiudf. No idea what happens, if meiudfs is used at txtsetup.sif.
Out of memory from 2008, maybe false memory after twelve years.
And there is ReactOS, there should be a ufs file system driver too. Could read USB mass storage devices.
There is no default udfs.sys at XP, there is cdfs.sys (ISO9660, Joliet file system) at XP only.
There are default udfs.sys at Vista and later. May support (USB) mass storage devices, may work at XP or fail.
Edited by cdob, 3 weeks ago.