That part is a good question, which I don't totally understand. There's a function Debugger::LoadPlugin() though, which accepts a path to a plugin to load. It's called there. This also appears to be exposed through the "plugin load" command.
On Tue, Aug 26, 2014 at 4:32 PM, Todd Fiala <tfi...@google.com> wrote: > I guess the thing to do is make sure we're certain we understand the > behavior, which is perhaps best captured in a test. (i.e. test it with the > RTLD_FIRST behavior where it does something, then verify it does something > different without the flag. Then, once we agree it is not useful behavior > for us, look at removing it). > > By valid plugin, you're referring to shared libraries, right? (What > plugins are we referring to here, at what load point?) > > > On Tue, Aug 26, 2014 at 4:29 PM, Zachary Turner <ztur...@google.com> > wrote: > >> Just as a counterpoint, unless I'm misunderstanding this code, I don't >> see it actually having a noticeable impact on stability. The search >> limiting will only be a factor in a case where you attempt to load >> something that *isn't a valid plugin*. It's already an error path. In >> fact, this code worked fine before the change was made, and was only made >> to imitate what appears to have been an optimization that was Mac-specific. >> The change for Mac doesn't seem to have been strictly necessary either, >> but just an optimization. It's actually not an optimization for Linux, >> because the dynamic loader will still search every module on linux, it will >> just fail anyway. >> >> >> On Tue, Aug 26, 2014 at 4:21 PM, Todd Fiala <tfi...@google.com> wrote: >> >>> Probably the way I'd look at this right now is that support in Linux is >>> a bit dicey and we're doing our best to stabilize (starting with single >>> path for remote/local debugging, and making that stable and fast). In an >>> effort to stabilize, I'd prefer to limit how much code change we do on the >>> Linux end until we have a more stable product. >>> >>> So while we could potentially take that out, I'd rather avoid making >>> changes just because it might be simpler, as it might also add yet another >>> error scenario on the Linux side. Right now I value similarity to MacOSX >>> execution over code reduction. Once we're a lot more stable on the Linux >>> side, I'd be much more interested in revisiting with some actual use cases >>> to see diffs in performance and scope of usage. >>> >>> Just my 2 cents... >>> >>> >>> On Tue, Aug 26, 2014 at 3:47 PM, Zachary Turner <ztur...@google.com> >>> wrote: >>> >>>> The review is up on the LLVM side. One point which was raised, and >>>> which I agree with, is that the presence of the string makes the class much >>>> heavier. This string is only needed to mimic MacOSX's RTLD_FIRST behavior >>>> on other posix platforms. However, going back through the history of when >>>> this was added, I never actually saw a use case from anyone saying "we >>>> *need* this on Linux". See the full original thread at [1]. But the TL;DR >>>> is that the flag is nice to have on MacOSX, and the filename comparison was >>>> added to Linux to maintain parity. >>>> >>>> If nobody actually knows of a specific example of why this is necessary >>>> on Linux, can we just remove this behavior on Linux? My understanding is >>>> that the only thing which will change by removing this for Linux is the >>>> following: Imagine a plugin X is loaded, and X has a library dependency on >>>> Y and Z. X doesn't contain the plugin Initialize or Terminate symbol, but >>>> Y or Z does. With the filename comparison code, LoadPlugin would fail, and >>>> without it, it would succeed and use the symbol found in Y or Z. I can >>>> understand that with the comparison the algorithm is a bit better, but it >>>> seems such an extremely unusual edge case that I don't think it's a big >>>> deal to remove it from the Linux side. >>>> >>>> Thoughts? >>>> >>>> [1] - >>>> http://thread.gmane.org/gmane.comp.debugging.lldb.devel/300/focus=302 >>>> >>>> >>>> On Thu, Aug 21, 2014 at 5:27 PM, Greg Clayton <gclay...@apple.com> >>>> wrote: >>>> >>>>> Sounds good to me. Hopefully if they don't want that they might accept >>>>> an extra boolean argument that can specify to only look in the current >>>>> shared library and then we can switch over to using LLVM's DynamicLibrary. >>>>> >>>>> > On Aug 21, 2014, at 4:22 PM, Zachary Turner <ztur...@google.com> >>>>> wrote: >>>>> > >>>>> > This seems like the only case we ever want, so I'm going to post a >>>>> patch to LLVM's DynamicLibrary class to use RTLD_FIRST on Apple, and a >>>>> similar method of checking the module filespec on other platforms, and see >>>>> if they accept it. If so, I will convert our Plugin code to use LLVM's >>>>> DynamicLibrary and then delete our DynamicLibrary >>>>> > >>>>> > >>>>> > On Thu, Aug 21, 2014 at 4:08 PM, Greg Clayton <gclay...@apple.com> >>>>> wrote: >>>>> > >>>>> > > On Aug 21, 2014, at 3:31 PM, Zachary Turner <ztur...@google.com> >>>>> wrote: >>>>> > > >>>>> > > Can someone explain this flag to me? >>>>> > >>>>> > It says "only look in this binary, don't look in any others. We are >>>>> looking for a plug-in initialization function and we don't want to get one >>>>> back from another dylib. >>>>> > >>>>> > As Enrico said, the email from a while back details this: >>>>> > >>>>> > http://comments.gmane.org/gmane.comp.debugging.lldb.devel/305 >>>>> > >>>>> > > I've read the documentation, but it's still not clear to me. If >>>>> you ask dlsym() to search some module X, why would it ever search modules >>>>> other than X? >>>>> > >>>>> > I don't know but it does. >>>>> > >>>>> > > >>>>> > > The reason I ask about this is that llvm support library already >>>>> has a DynamicLibrary class whose purpose almost exactly matches what we're >>>>> using the Host::DynamicLibrary related functions for. However, it doesn't >>>>> use the RTLD_FIRST flag, and so I'm not sure what the implications are of >>>>> us using it and deleting our own DynamicLibrary code. >>>>> > >>>>> > It would be nice if we could specify this flag so we either find the >>>>> symbol from libx.dylib or we don't. We don't want to find the symbol in >>>>> liby.dylib and call it in our case. >>>>> > >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> lldb-dev mailing list >>>> lldb-dev@cs.uiuc.edu >>>> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev >>>> >>>> >>> >>> >>> -- >>> Todd Fiala | Software Engineer | tfi...@google.com | 650-943-3180 >>> >> >> > > > -- > Todd Fiala | Software Engineer | tfi...@google.com | 650-943-3180 >
_______________________________________________ lldb-dev mailing list lldb-dev@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
