The search for the correct amount of split-lock misery [LWN.net]

The search for the correct amount of split-lock misery

Posted Oct 21, 2022 12:19 UTC (Fri) by mathstuf (subscriber, #69389)
In reply to: The search for the correct amount of split-lock misery by bartoc
Parent article: The search for the correct amount of split-lock misery

Mmm, yes, the fun problem of figuring out "what did this program do to my machine?" when trying to uninstall it. Not sure I'd like to import that particular behavior from Windows.

Incidentally, more programs supporting `/etc/prog.d/*.conf`-style configuration would be greatly appreciated :) .

> restoring misery mode when the game has exited.

ABAB problems sound fun with this. Also sounds like a maze full of fun error code paths that will never be reliably tested.

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The search for the correct amount of split-lock misery

Posted Oct 21, 2022 12:29 UTC (Fri) by bartoc (guest, #124262) [Link] (4 responses)

Yeah. Though actually another option might be to just have wine know how to bump around the allocations in question to avoid the split-locks in the first place. It would have to be a game-specific hack probably.

I wonder if windows has compat shims for this kinda stuff.

The search for the correct amount of split-lock misery

Posted Oct 21, 2022 15:00 UTC (Fri) by mathstuf (subscriber, #69389) [Link] (2 responses)

Yeah, it's done those kinds of things: https://arstechnica.com/gadgets/2022/10/windows-95-went-t...

TheOldNewThing blog by Raymond Chen also has lots of tales to this effect: https://devblogs.microsoft.com/oldnewthing/

The search for the correct amount of split-lock misery

Posted Oct 21, 2022 23:40 UTC (Fri) by bartoc (guest, #124262) [Link] (1 responses)

yeah ofc, but I mean _this specific problem_

The search for the correct amount of split-lock misery

Posted Oct 22, 2022 23:26 UTC (Sat) by developer122 (guest, #152928) [Link]

Not possible, see comment below. This approach was also suggested during the kernel syscall emulation saga and also shot down then too.

The search for the correct amount of split-lock misery

Posted Oct 22, 2022 23:25 UTC (Sat) by developer122 (guest, #152928) [Link]

This is not possible.

This same suggestion *also* came up during the kernel syscall emulation work. It was suggested that instead of having the kernel reroute attempts by a program to call a windows kernel syscall, wine could simply scan for and patch any such attempts.

This is not only hideously complicated and unreliable, it also doesn't work at all with exactly the class of programs we're interested with: Games.

They frequently include a wide variety of very gnarly anti-tampering features which cannot be automatically overcome. It is for this reason wine seeks to emulate the environment around the program, and never ever attempts to reach inside it.