[cobalt-developers] Re: Cobalt MIPS CPU

[Andrew Tuckey <tuckey@xxxxxxxxxxxx>]

> On Wed, May 31, 2000 at 12:41:51PM -0400, Kevin D wrote:
> : I am interested in finding out more about the cpu in the cobalt RAQ3i. I
> : want eventually to write some C++ code for it, and I was wondering if the
> : instruction set were compatible with the x86 instruction set (I believe i
> : read this somewhere?) My concern of course is being able to debug and
> : compile on my Intel x86 workstation and then installing the software on the
> : RAQ.
> 
> There are some noticable difference in the MIPS vs Intel instructions set
> (hint: one is better, and Intel doesn't make it!).  I recommend See Mips Run
> by Dominic Sweetman to learn more about the MIP arch.
>  
> : Also, I am slightly interested in installing some programs on the RAQ that
> : are not opensource, and come in only x86 flavor.
> 
> If you are using the came compiler, this should be fairly painless.  I have
> recently been working on a non-opensource project and the port to MIPS
> was simply:
> 
> make
> 
> :)
> 
> Of course that it not always the case.

I have some questions about the 64-bit 'ness of the MIPS processors used in
the Qube and RaQ(2).  

As far as I'm aware the low-end Qube and the RaQ use the RM5320 MIPS processor
(175MHz clock) made by QED in Santa Clara, CA.

The high-end Qube (what I have) and the RaQ2 use the RM5321 MIPS processor
(250MHz clock), also made by QED.  Both of these have 64-bit superscalar
processor cores and a 32-bit system address bus (presumably to keep the
packages small).


In the process of porting CyberPatrol to a Qube I was keen to check for word
length dependencies; I was using the CyberPatrol Linux/Intel port as a
reference.  The output of configure is :

Intel:
  checking host system type... i686-pc-linux-gnu
  checking whether byte ordering is bigendian... (cached) no
  checking size of unsigned int... (cached) 4
  checking size of unsigned short... (cached) 2
  checking size of unsigned long... (cached) 4


MIPS: 
  checking host system type... mipsel-unknown-linux-gnu
  checking whether byte ordering is bigendian... (cached) no
  checking size of unsigned int... (cached) 4
  checking size of unsigned short... (cached) 2
  checking size of unsigned long... (cached) 4

I don't see any 64-bit 'ness here. 

Also /usr/include/limits.h is almost identical for both systems.  limits.h for
the MIPS is :


    /* These assume 8-bit `char's, 16-bit `short int's,
         and 32-bit `int's and `long int's.  */
    
    /* Number of bits in a `char'.  */
    #  define CHAR_BIT      8
    
    /* Minimum and maximum values a `signed char' can hold.  */
    #  define SCHAR_MIN     (-128)
    #  define SCHAR_MAX     127
    
    /* Maximum value an `unsigned char' can hold.  (Minimum is 0.)  */
    #  define UCHAR_MAX     255
    
    /* Minimum and maximum values a `char' can hold.  */
    #  ifdef __CHAR_UNSIGNED__
    
    /* Minimum and maximum values a `signed short int' can hold.  */
    #  define SHRT_MIN      (-32768)
    #  define SHRT_MAX      32767
    
    /* Maximum value an `unsigned short int' can hold.  (Minimum is 0.)  */
    #  define USHRT_MAX     65535
    
    /* Minimum and maximum values a `signed int' can hold.  */
    #  define INT_MIN       (- INT_MAX - 1)
    #  define INT_MAX       2147483647
    
    /* Maximum value an `unsigned int' can hold.  (Minimum is 0.)  */
    #  ifdef __STDC__
    #   define UINT_MAX     4294967295U
    #  else
    #   define UINT_MAX     4294967295
    #  endif
    
    /* Minimum and maximum values a `signed long int' can hold.  */
    #  ifdef __alpha__
    #   define LONG_MAX     9223372036854775807L
    #  else
    #   define LONG_MAX     2147483647L
    #  endif
    #  define LONG_MIN      (- LONG_MAX - 1L)
    
    /* Maximum value an `unsigned long int' can hold.  (Minimum is 0.)  */
    #  ifdef __alpha__
    #   define ULONG_MAX    18446744073709551615UL
    #  else
    #   ifdef __STDC__
    #    define ULONG_MAX   4294967295UL
    #   else
    #    define ULONG_MAX   4294967295L
    #   endif
    #  endif

64-bit variables are only defined for the __alpha__.


Is there anything in the MIPS processor that is 64-bits long?  Is limits.h
incorrect?


-- 
Andrew Tuckey
The Netherlands.      	      Email: tuckey@xxxxxxxxxxxx