The i386 GNU/Hurd ELF core format actually follows the uaccess gregset_t array format, not the Mach thread state format. This fixes gdb reading it.
* gdb/i386gnu-nat.c (CREG_OFFSET): New macro. (creg_offset): New array. (CREG_ADDR): Use creg_offset instead of reg_offset. --- a/gdb/i386gnu-nat.c.original 2013-02-11 00:46:02.000000000 +0000 +++ b/gdb/i386gnu-nat.c 2013-02-11 00:48:09.000000000 +0000 @@ -56,8 +56,21 @@ REG_OFFSET (ds), REG_OFFSET (es), REG_OFFSET (fs), REG_OFFSET (gs) }; +/* Offset to the greg_t location where REG is stored. */ +#define CREG_OFFSET(reg) (REG_##reg * 4) + +/* At CREG_OFFSET[N] is the offset to the greg_t location where + the GDB register N is stored. */ +static int creg_offset[] = +{ + CREG_OFFSET (EAX), CREG_OFFSET (ECX), CREG_OFFSET (EDX), CREG_OFFSET (EBX), + CREG_OFFSET (UESP), CREG_OFFSET (EBP), CREG_OFFSET (ESI), CREG_OFFSET (EDI), + CREG_OFFSET (EIP), CREG_OFFSET (EFL), CREG_OFFSET (CS), CREG_OFFSET (SS), + CREG_OFFSET (DS), CREG_OFFSET (ES), CREG_OFFSET (FS), CREG_OFFSET (GS) +}; + #define REG_ADDR(state, regnum) ((char *)(state) + reg_offset[regnum]) -#define CREG_ADDR(state, regnum) ((const char *)(state) + reg_offset[regnum]) +#define CREG_ADDR(state, regnum) ((const char *)(state) + creg_offset[regnum]) /* Get the whole floating-point state of THREAD and record the values