Opening a .pkg now offers to install it, the way a .zip does - see the new
InstallPkgScreen, which shows what the update patches, what it'll take up
on disk (exact, since package contents aren't compressed) and where it's
going. The package's PS3-style USRDIR/CONTENT wrapping is stripped so the
files land where the PSP expects them, in PSP/GAME/<DISC_ID>.
Booting a disc then looks for PSP/GAME/<DISC_ID>/PBOOT.PBP and boots that
instead of the disc's own EBOOT, leaving the disc mounted - so the update
overrides the files it ships and the disc supplies the rest. The update's
DISC_ID has to match; a DISC_VERSION mismatch only warns, since updates do
get used with slightly different dumps in practice.
Verified against the whole corpus: every one installs, and the
digital NP* update/base-image pairs that could be assembled all boot the
patch rather than the disc's executable. That includes Super Robot Taisen
Operation Extend from a real NPUMDIMG EBOOT.PBP, which settles that
ISO.BIN.EDAT does not re-key the PBOOT - a digital title's patched EBOOT is
encrypted exactly like a UMD one. On the UMD side, the patched
LittleBigPlanet reads PATCH.ARC out of the install alongside the disc's own
archive.
The DISC_VERSION warning turns out to be load-bearing: many of the pairs
mismatch, because the dumps in circulation are later disc revisions than the
updates were built against. docs/pkg_notes.md has the numbers, and the one
thing that doesn't work - PGD-wrapped .sprx modules, which
sceKernelLoadModuleNpDrm can't load.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
