Re: [Crash-utility] [PATCH 0/4] MIPS support

On Mon, Jan 12, 2015 at 11:00:08AM -0500, Dave Anderson wrote: > I don't know what the real-world usage is with respect to little-endian > vs. big-endian 32-bit MIPS, but you got here first. And in the > future, it should be simple enough to support big-endian MIPS as > well, i.e., in the same manner that both little- and big-endian PPC64 > are supported. I attempted to have a quick look at big-endian while making the patch (it's easy to emulate big-endian MIPS too on QEMU), and if I understand correctly from the PPC handling, the host endianness needs to match the target endianness. So that means we can't analyze big-endian MIPS dumps on x86/x86-64 hosts, right? The MIPS systems which I personally plan to use this for are little-endian, and the analysis will be done on x86-64 hosts. > Running cscope from the gdb-7.6 subdirectory on down shows only > this single reference to convert: > > sim/mips/sim-main.h Convert 774 #define Convert(rm,op,from,to) convert > (SIM_ARGS, rm, op, from, to) > > But it doesn't show any callers to Convert() or convert(). So > it appears to exist as a non-static function in "sim/mips/cp1.c" > that nobody calls? In any case, please make the convert() name > change down in the gdb-7.6/sim/mips code, and update gdb-7.6.patch > accordingly. Done. Convert() is used in the mips.igen file in the same directory, which appears to be used to generate C code and compile it as part of the build process. > Also in defs.h, please put the task_struct_thread_reg29 and > task_struct_thread_reg31 offsets at the end of the offset_table > structure. Again, new entries to that structure should always > be appended to the structure so that it won't break the usage > of OFFSET() by pre-existing extension modules. Also, you should > add their offset value displays to dump_offset_table() for use > by "help -o", and in that function, you can display it next to > the other task_struct_thread_xxx offsets. Done. > On another note, there should be an understandable and clean > protection mechanism against running a target=MIPS binary on a > live host system. So when attempting to run a target=ARM crash > binary on an x86/x86_64 host, it fails like so: > > $ sudo ./crash > crash: compiled for the ARM architecture > > With your target=MIPS binary, it shows this confusing error message: > > crash: cannot resolve "cpu_data" > > It's a small check that can be put at the beginning of mips_init(). > I presume that you used ppc.c as a template, so if you'd like, you > can add the same fix there as well. ppc.c doesn't have that check, but I've added it to mips.c based on what's in arm.c. > Lastly (at least at this point), can you update the README[] strings array > in help.c to show that MIPS is a supported architecture, and that it can > be build as a "target=" binary? Done. > Oh, and thanks very much for the sample vmcores. I'll keep them around for > future > testing. BTW, the System.map file is completely unnecessary -- is there a > reason > you included it? Not really. I never used it but thought "just in case" while zipping up the dumps + vmlinux. Rabin -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility