User:Petr-akhlamov/Compatibility mode

From ReactOS Wiki
< User:Petr-akhlamov
Revision as of 22:29, 3 January 2018 by Luca090902 (talk | contribs) (Links: Word corrected.)
Jump to: navigation, search

Mark Jassen implements this function in ReactOS.

NT 6.0 API support

  • CORE-11288 - Currently ReactOS targets only Windows 2003. Developer plans to implement a mechanism for user mode applications to be able to use APIs from Windows NT 6.0 and later, while still keeping the original 2k3 environment.
    • CORE-11289 - Research and document Windows compatibility settings
    • CORE-11290 - Make sure the loader respects compatibility settings
    • CORE-11291 - Create Windows 7 spec files for core DLLs
    • CORE-11292 - Core win32 API organization
    • CORE-11293 - Research kernel requirements for NT 6+ user mode APIs

Compatibility mode implementation



NtApphelpCacheControl kernel function used by AppHelp for save 200 last runed apps in RAM for more fastly search. After exit the list is saved tin the registry, and loaded back at running.

Implement apphelp sdb layer

Implement most Sdb* api's, related to reading and writing of Sdb files.

Sdb files are application compatibility databases, containing information about known bad applications, and a list of 'shims' to be applied to those applications.

As base used is

Tab in shortcut properties

Tab in the explorer

In newer windows versions this is implemented as shell extension (acppage.dll). This uses the functions SetPermLayerState, SdbGetPermLayerKeys.

Now it's implemented with function which allows apply needed "layers".

Integrate apphelp

Integrate apphelp in process creation (LDR), COM, msi and Driver loading.

  • CORE-10368
    • 03-06-2017 Integrate apphelp in process creation was started CORE-13284
      • June 27 first patch was published
      • June 29 function SdbpMatchExe was implemented
      • July 1 integration apphelp to process creation was implemented

Shim infrastructure

It implement base infrastructure that shims can leverage to do their work.

Provide default shims

It provide:


It do helper functions to register shims, and to handle common tasks.

First commit - r73461.

Shim data in links

Apply compatibility environment for lnk, and not *exe-file.


  • 05-09-2015 component NtApphelpCacheControl was implemented in the kernel (CORE-9914)
  • 31-03-2016 library apphelp.dll was added (CORE-10367)
  • 28-05-2016 List of "emulated" API versions was added (CORE-11299)
  • 16-12-2016 settings for Resolution/Bitdepth/DisableThemes was added (CORE-11927)
  • 22-04-2017 - implement custom compatibility mode selection as shell extension acppage
  • 19-05-2017 Initial implementation of integrate apphelp to process creation (LDR), COM, msi and Driver loading was added (CORE-10368)
  • 29-06-2017 SdbpMatchExe function was implemented, allowing to match applications/files based on properties (CORE-13284)
  • 01-07-2017:
  • 30-07-2017 ShimLib implementation was finished
  • 17-08-2017 Compatibility mode was enabled default (but, he can't will be applied to system files - in system32 and WinSxS)

Compatibility apps

Apps, which works in compatibility mode:

  • VMware Horizon Client for 32-bit Windows[1][2]
  • Windows Media Player 6.4[3]


In ReactOS sources are libraries advapi32_vista, kernel32_vista, ntoskrnl_vista and ntdll_vista. You can think, what they are for implementation Vista+ API in ReactOS, but it's mistake. Right now these are there to provide needed functions for linking Wine's dlls which project use. [4]