site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com I've created <rdar://8199262> regarding the issue of new loaders, to help the chances this get added for both Wine & XBinary. - Antoine ps: Terry: is it voluntary I get radio silence offlist ? On 2010-07-14, at 2:22 PM, Terry Lambert wrote:
Hi, I'm the one who rewrote the exec code several times since Panther, including implementing the posix_spawn() code, and adding the execsw[] table, as well as dealing with many of the issues of multithreaded [v]fork() and exec() introduced by GCD.
No data table is likely to become KPI, for the simple reason that data interfaces can't be as easily revised as procedural interfaces, and locking it into a specific data structure design is simply bad engineering practice.
Likewise, any procedural KPI for adding your own entries is unlikely to permit overriding existing entries, which would, in my preference, be in read-only pages whose mappings are not under kernel control, and not accessible by physical address. This would be for security reasons. New entries, if permitted, would most likely go at the end of the table. This would accommodate Evan's PELoader code for the modified COFF executables used for Windows .EXE files, since they don't match the "magic numbers" for existing entries, and things like Amit Singh's ELF loader code, but *NOT* accommodate interposition, for which other KPI would be preferred.
I'm aware of how the execsw[] hacks work in both cases, and the use is, as I've explained before, unsupported, although no one has gone out of their way to explicitly break it, and probably no one will unless there's a compelling reason to change the data structure. But people should be aware of the issues surrounding the use of this type of hack.
If you have a specific request for KPI for this sort of thing, or for other reasons, please file a bug report including your rationale and the problem(s) you are trying to solve.
Without a bug report to hang the code changes off of, we have to arrive at it ourselves as desired feature work, and without a customer, it's not likely to make a product schedule unless it's a blindingly brilliant idea.
-- Terry
On Jul 14, 2010, at 9:46 AM, Antoine Missout wrote:
I hope Apple will provide an API to add/remove entries in execsw. They could at least leave a few blank entries :P We also modify the table for other reasons in a product we'll soon release, and we might conflict if our kext and yours are not unloaded in reverse order of loading. Not sure how we can avoid this without official KPIs. - Antoine
On 2010-07-14, at 10:12 AM, Evan Lojewski wrote:
I neglected to mention that I've only used this approach on Snow Leopard. When using it on Leopard, I did run into one or two issues. I'll setup a Leopard machine tonight to verify if it works or not.
I'd suggest placing the symbol kext inside of your real kext (Contents/PlugIns/MissyingSymbols.kext) rather than placing it in System.kext. I'd also suggest that you don't use com.apple.kpi for the bundle identifier, use your own identifier for this.
On Snow Leopard (not sure about leopard), kextstat does report the com.apple.kpi.* and com.apple.kernel.* kexts. When I load the symbol kext it also shows up.
If you want to test a kext on Leopard that I know works perfectly on Snow Leopard using this method, this (http://dl.dropbox.com/u/863180/wineHelper.kext.zip) should work, however I haven't tested it on Leopard. This kext just modifies the _execsw variable to cause the kernel to load wine when an .exe file is run.
Evan Lojewski
On Wed, Jul 14, 2010 at 6:21 AM, Platon Fomichev <pfomichev@elverils.com> wrote:
Dear Evan
I tried your approach (Leopard 10.5.8) and indeed it sounds like a salvation. Alas it does not work. I will show my progress:
1) Created a 'symbol' kext that has several exports. Placed it into PlugIns, touched the 'Extensions' and tried to load it.
iMac:Development stauff$ sudo kextload /System/Library/Extensions/System.kext/PlugIns/MissingSymbols.kext/ extension /System/Library/Extensions/System.kext/PlugIns/MissingSymbols.kext/ is a kernel component
After reboot it does not show up in kextstat, and probably won't as I haven't found any traces of system loading PlugIns module, they are hardcoded into KernelConfigTables.cpp
2) Created a 'real' kext that links against 'symbol' kext. Tried loading it. Here is a log:
kextload: mapping module file /System/Library/Extensions/System.kext/PlugIns/System6.0.kext/kernel.6.0 kextload: module file /System/Library/Extensions/System.kext/PlugIns/System6.0.kext/kernel.6.0 is already mapped kextload: mapping module file /System/Library/Extensions/System.kext/PlugIns/MissingSymbols.kext/MissingSymbols <-------- Here is symbol kext kextload: module file /System/Library/Extensions/System.kext/PlugIns/MissingSymbols.kext/MissingSymbols is already mapped kextload: mapping module file /System/Library/Extensions/System.kext/PlugIns/BSDKernel.kext/BSDKernel kextload: module file /System/Library/Extensions/System.kext/PlugIns/BSDKernel.kext/BSDKernel is already mapped kextload: mapping module file /System/Library/Extensions/System.kext/PlugIns/Unsupported.kext/Unsupported kextload: module file /System/Library/Extensions/System.kext/PlugIns/Unsupported.kext/Unsupported is already mapped kextload: mapping module file /System/Library/Extensions/System.kext/PlugIns/Libkern.kext/Libkern kextload: module file /System/Library/Extensions/System.kext/PlugIns/Libkern.kext/Libkern is already mapped kextload: mapping module file /Users/stauff/cvs/wm/client/osx/build/Development/testnke.kext/Contents/MacOS/testnke kextload: module file /Users/stauff/cvs/wm/client/osx/build/Development/testnke.kext/Contents/MacOS/testnke is already mapped kextload: patching C++ code in module /Users/stauff/cvs/wm/client/osx/build/Development/testnke.kext/Contents/MacOS/testnke kextload: link/loading file /System/Library/Extensions/System.kext/PlugIns/System6.0.kext/kernel.6.0 kextload: link/loading file /System/Library/Extensions/System.kext/PlugIns/MissingSymbols.kext/MissingSymbols <--- It is even loading kextload: link/loading file /System/Library/Extensions/System.kext/PlugIns/BSDKernel.kext/BSDKernel kextload: link/loading file /System/Library/Extensions/System.kext/PlugIns/Unsupported.kext/Unsupported kextload: link/loading file /System/Library/Extensions/System.kext/PlugIns/Libkern.kext/Libkern kextload: opaque link for /Users/stauff/cvs/wm/client/osx/build/Development/testnke.kext/Contents/MacOS/testnke kextload: link/loading file /Users/stauff/cvs/wm/client/osx/build/Development/testnke.kext/Contents/MacOS/testnke kextload: allocated 28672 bytes in kernel space at 0x41679000 kextload: using load address of 0x41679000 kextload: kmod name: com.aep.kext.idprint kextload: kmod start @ 0x4167eeee (offset 0x52ae) kextload: kmod stop @ 0x4167ef02 (offset 0x52c2) kextload: module com.aep.kext.idprint created as # 114 at address 0x41679000, size 28672 kextload: adding reference from com.aep.kext.idprint (114) to com.apple.kpi.libkern (5) kextload: adding reference from com.aep.kext.idprint (114) to com.apple.kpi.unsupported (7) kextload: adding reference from com.aep.kext.idprint (114) to com.apple.kpi.bsd (2) kextload: adding reference from com.aep.kext.idprint (114) to com.apple.kpi.missingsymbols (0) <--- bad sign?? ID of missing symbols is zero kextload: kmod retain failed for com.aep.kext.idprint; destroying kmod kextload: a link/load error occured for kernel extension testnke.kext/ kextload: clearing all version/dependency relationships among kernel extensions link/load failed for extension testnke.kext/ (run kextload with -t for diagnostic output)
What am I doing wrong, please advise.
Best regards, Platon
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