* Run programs, scripts and AppImages from the desktop
Windows programs open with the Proton Steam has chosen, and a Steam game's own
launch program is handed to Steam. x86-64 Linux programs and game scripts run
under FEX, and an exec the kernel refuses goes to droiddeck-open through
libblsession's binfmt.c. Programs on noexec shared storage pass KIO's checks; a
folder of Linux programs there, and sharun AppImages, are added by the app once
and run from the copy. Executable scripts run without KIO's prompt, mpv plays
on the software desktop, FEXServer's socket moves under XDG_RUNTIME_DIR, and
Proton runtimes no longer show up as games.
* Switch to Desktop from Big Picture without Deck mode
Big Picture's Switch to Desktop asks the client's SteamOS manager, which the
client only has when started as SteamOS (Deck mode). Without it the request
failed and the screen stayed on "Switching to Desktop..." for good. The live
compat helper now sees the request on its way to the client and hands it to
steamos-session-select, which opens the KDE desktop as Deck mode already did.
* Run x86 programs from shared storage where they lie
FEX asks for the guest's PROT_EXEC when it maps a program or library, which
the kernel refuses on noexec shared storage; FEX never runs those pages
itself, so libblsession maps them without it in FEX's processes. An x86
game, its libraries and its start script now run in place instead of being
copied in; only native code on noexec storage is still copied.
A Steam library's games are never copied, and a Linux game's launch program
opened from the desktop goes to Steam like a Windows one.
With Second library on Automatic, every writable Games folder is now a
Steam library: it gets the same private prefix and tool binds as the card,
the app hands the session the list (BL_STEAM_LIBRARIES), and
droiddeck-steam-library registers, relabels and forgets entries from it.
Steam offers them in the install dialog as "<folder> (<volume>)", and
Proton mapping, esync, the redist seeder, desktop entries and the compat
beat read every registered library instead of only the card. Games folder
libraries stop at the fast path's bind budget.
Steam's preallocation on Android's FUSE storage either failed outright
(NTFS answers EPERM, so installs were cancelled as "not enough disk
space") or zero-filled the whole download first (exFAT, minutes for a
small game). After fallocate is refused, the Steam client's ftruncate
extension of its own staging files is reported as done; the writes that
follow fill the file. A 76 MB install to a USB SSD now preallocates
instantly instead of taking about 3.5 minutes.
A library that is not there is left out of the list and forgotten until
it returns, imports whose folder is missing are set aside rather than
offered as broken installs, and the front end refreshes when storage is
mounted or removed.
MaxsTechReview