On 1/31/2012 4:15 AM, Julian Seward wrote: > > (You didn't reply-all on this; I assume that was intended)
I did; thanks ... >> Your comments on the probable (non)utility of the instruction are >> suggestive as to why the copied-over x86 code is commented out. >> Unsurprisingly, simply uncommenting it did not work :-) . > > It might be that the 32- and 64-bit versions generate slightly different > in-memory formats. You'll need to read the Intel docs closely. You may > find it useful to play with some or all of the following test programs > (ymmv, #include<disclaimer.h> etc) > > ./memcheck/tests/amd64/fxsave-amd64.c > ./memcheck/tests/x86/fxsave.c > ./VEX/test/fsave.c > ./VEX/test/fxsave.c > > One thing that's important to understand is that Valgrind simulates > x87 style FP only to 64 bit precision. Hence the memory image that its > fsave instruction makes will differ in the lowest, uh, 16 or so mantissa > bits compared to running on real hardware. Some of the test cases above > take that into account. All very helpful, Julian. What I meant was that the commented out code would not compile. Among other things, it refers to helpers over in x86 code not visible to the amd64 code I was trying to modify. You are correct that the (AMD) docs to which I referred describe several different in-memory formats and it will be necessary to determine which one happens in 64-bit mode. That is something I think I had best verify on an actual machine as well, since the docs are not simple to follow. In particular I want to make sure that I understand the effect of the 0x66 size prefix on these instructions! Regards -- Eliot ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
