Re: [Crash-utility] question about phys_base

----- Original Message ----- > At 02/28/2012 04:52 PM, HATAYAMA Daisuke Wrote: > >>> In general, such characteristic should not be used. You should prepare > >>> a solid interface. Even if using them, it should be limited to as > >>> workaround to avoid some issue. > >>> > >>> Why not use qemu's CPU state? Include it as note information with good > >>> name, and we can use it to distinguish which. Like: > >>> > >>> $ readelf -n vmcore > >>> > >>> Notes at offset 0x000001c8 with length 0x00000838: > >>> Owner Data size Description > >>> CORE 0x00000150 NT_PRSTATUS (prstatus structure) > >>> CORE 0x00000150 NT_PRSTATUS (prstatus structure) > >>> QEMU 0x00000557 Unknown note type: (0x00000000) > >>> > >>> Or QEMUCPUState is better? > >> > >> Good idea. I will try it, and hope gdb can also work. > >> > > > > Tools basically ignore unknown notes. Looking into gdb, it appears to > > ignore unknown information. > > > > static bfd_boolean > > elfcore_grok_note (bfd *abfd, Elf_Internal_Note *note) > > { > > const struct elf_backend_data *bed = get_elf_backend_data (abfd); > > > > switch (note->type) > > { > > default: > > return TRUE; > > <cut> > > > > You might need to add new command to output contents of new note if > > it's necessary. > > My goal is: > 1. gdb uses NT_PRSTATUS, and can work well > 2. crash uses unknown notes, and can get phys_base from it. > > Another question: > > What is QEMUCPUState? I donot find its definition? It's just the note's name character string. Either "QEMU", "QEMUCPUState", or whatever unique character string you prefer would suffice. > What note->type shoule be for "QEMU"? If we choose an unused value, the > value may be used in the future. Why not do the same thing as the "VMCOREINFO" note, and leave it as an "illegal/unknown" type of 0:: $ cat /usr/include/elf.h ... [ cut ] ... /* Legal values for note segment descriptor types for core files. */ #define NT_PRSTATUS 1 /* Contains copy of prstatus struct */ #define NT_FPREGSET 2 /* Contains copy of fpregset struct */ #define NT_PRPSINFO 3 /* Contains copy of prpsinfo struct */ ... $ $ readelf -a vmcore ... [ cut ] ... Notes at offset 0x00000190 with length 0x00000f1c: Owner Data size Description CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) CORE 0x00000150 NT_PRSTATUS (prstatus structure) VMCOREINFO 0x000003e4 Unknown note type: (0x00000000) $