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revision 23 by dpavlin, Mon Oct 8 16:19:37 2007 UTC revision 24 by dpavlin, Mon Oct 8 16:19:56 2007 UTC
# Line 10  Line 10 
10    
11  <!--  <!--
12    
13  $Id: experiments.html,v 1.96 2006/02/18 13:15:20 debug Exp $  $Id: experiments.html,v 1.102 2006/06/12 10:21:12 debug Exp $
14    
15  Copyright (C) 2003-2006  Anders Gavare.  All rights reserved.  Copyright (C) 2003-2006  Anders Gavare.  All rights reserved.
16    
# Line 65  that you do two things: Line 65  that you do two things:
65    
66  <p>  <p>
67  <ul>  <ul>
68    <li>Build and install a cross-compiler for MIPS.    <li>Build and install a cross-compiler for your chosen target.
69    <li>Compile this hello world program, and run it in the emulator.          GCC is usually a good compiler choice, because it is portable
70            and in wide-spread use. (Other compilers should work too.)
71    
72      <p>
73      <li>Compile the Hello World demo program for your chosen target, and run
74            it in the emulator.
75  </ul>  </ul>
76    
77  <p>  <p>The Hello World demo program is included in the GXemul source
78  <table border="0"><tr><td width="40">&nbsp;</td><td>  code distribution, in the <a href="../demos/hello/"><tt>demos/hello/</tt></a>
79  <pre>  subdirectory. The README files in the demo directories have several
80  <font color=#f00000>/*  Hello world for GXemul  */  examples of how the demo programs can be built.
   
 /*  Note: The cast to a signed int causes the address to be sign-extended  
     correctly to 0xffffffffb00000xx when compiled in 64-bit mode  */  
 </font><font color=#a0a0a0>#define      PUTCHAR_ADDRESS         ((signed int)0xb0000000)  
 #define HALT_ADDRESS            ((signed int)0xb0000010)  
   
 </font><font color=#c000c0>void </font><font color=#000000><a name="printchar">printchar</a>(</font><font color=#c000c0>char </font><font color=#000000>ch)  
 {  
         *((</font><font color=#c000c0>volatile unsigned char </font><font color=#000000>*) PUTCHAR_ADDRESS) = ch;  
 }  
   
 </font><font color=#c000c0>void </font><font color=#000000><a name="halt">halt</a>(</font><font color=#c000c0>void</font><font color=#000000>)  
 {  
         *((</font><font color=#c000c0>volatile unsigned char </font><font color=#000000>*) HALT_ADDRESS) = 0;  
 }  
   
 </font><font color=#c000c0>void </font><font color=#000000><a name="printstr">printstr</a>(</font><font color=#c000c0>char </font><font color=#000000>*s)  
 {  
         </font><font color=#c000c0>while </font><font color=#000000>(*s)  
                 printchar(*s++);  
 }  
   
 </font><font color=#c000c0>void </font><font color=#000000>f(</font><font color=#c000c0>void</font><font color=#000000>)  
 {  
         printstr(</font><font color=#00c000>"Hello world\n"</font><font color=#000000>);  
         halt();  
 }  
 </font></pre>  
 </td></tr></table>  
   
 <p>(This hello world program is available here as well:  
 <a href="hello_mips.c"><tt>hello_mips.c</tt></a>)  
   
 <p>I recommend that you build a GCC cross compiler for the  
 <b>mips64-unknown-elf</b> target, and install it. Other compilers could  
 work too, but GCC is good because of its portability. Then try to compile  
 and link the hello world program:  
 <pre>  
         $ <b>mips64-unknown-elf-gcc -O2 hello_mips.c -mips4 -mabi=64 -c</b>  
         $ <b>mips64-unknown-elf-ld -Ttext 0xa800000000030000 -e f hello_mips.o -o hello_mips --oformat=elf64-bigmips</b>  
         $ <b>file hello_mips</b>  
         hello_mips: ELF 64-bit MSB mips-4 executable, MIPS R3000_BE, version 1 (SYSV), statically linked, not stripped  
         $ <b>gxemul -q -E testmips hello_mips</b>  
         Hello world  
   
         $ <b>mips64-unknown-elf-gcc -O2 hello_mips.c -c</b>  
         $ <b>mips64-unknown-elf-ld -Ttext 0x80030000 -e f hello_mips.o -o hello_mips</b>  
         $ <b>file hello_mips</b>  
         hello_mips: ELF 32-bit MSB mips-3 executable, MIPS R3000_BE, version 1 (SYSV), statically linked, not stripped  
         $ <b>gxemul -q -E testmips hello_mips</b>  
         Hello world  
 </pre>  
   
 <p>  
 As you can see above, a GCC configured for mips64-unknown-elf can produce  
 both 64-bit and 32-bit binaries. If you don't want to run the entire  
 Hello World program, but want to single-step through the execution to  
 learn more about how MIPS programs run, then add -V to the command line:  
81    
82  <p>  <p>Hopefully this is enough to get you inspired. :-)
 <pre>  
         $ <b>gxemul -V -E testmips hello_mips</b>  
         ..  
         GXemul&gt; <b>r</b>  
         cpu0:    pc = a800000000030078    <f>  
         cpu0:    hi = 0000000000000000    lo = 0000000000000000  
         cpu0:    zr = 0000000000000000    at = 0000000000000000  
         cpu0:    v0 = 0000000000000000    v1 = 0000000000000000  
         ..  
         cpu0:    gp = a8000000000780c0    sp = ffffffffa0007f00  
         cpu0:    fp = 0000000000000000    ra = 0000000000000000  
         GXemul&gt; <b>s 15</b>  
         &lt;f&gt;  
         a800000000030078: 67bdfff0      daddiu  sp,sp,-16  
         a80000000003007c: 3c04a800      lui     a0,0xa800  
         a800000000030080: 3c010003      lui     at,0x3  
         a800000000030084: 64840000      daddiu  a0,a0,0  
         a800000000030088: 642100b8      daddiu  at,at,184  
         a80000000003008c: 0004203c      dsll32  a0,a0,0  
         a800000000030090: 0081202d      daddu   a0,a0,at  
         a800000000030094: ffbf0000      sd      ra,0(sp)  [0xffffffffa0007ef0, data=0x0000000000000000]  
         a800000000030098: 0c00c00a      jal     0xa800000000030028 &lt;printstr&gt;  
         a80000000003009c: 00000000 (d)  nop  
           &lt;printstr("Hello world\n",0,0,0,..)&gt;  
         &lt;printstr&gt;  
         a800000000030028: 67bdfff0      daddiu  sp,sp,-16  
         a80000000003002c: ffb00000      sd      s0,0(sp)  [0xffffffffa0007ee0, data=0x0000000000000000]  
         a800000000030030: ffbf0008      sd      ra,8(sp)  [0xffffffffa0007ee8, data=0xa8000000000300a0]  
         a800000000030034: 90820000      lbu     v0,0(a0)  [0xa8000000000300b8 = $LC0, data=0x48]  
         a800000000030038: 00021600      sll     v0,v0,24  
         GXemul&gt; <b>print v0</b>  
         v0 = 0x0000000048000000  
         GXemul&gt; <b>_</b>  
 </pre>  
   
 <p>The syntax of the single-step debugger shouldn't be too hard to grasp.  
 Type "<tt>s</tt>" to single-step one instruction. For some commands (e.g.  
 the single-step command), just pressing enter on a blank line will cause  
 the last command to be repeated. Type "<tt>quit</tt>" to quit.  
   
 <p>  
 Hopefully this is enough to get you inspired. :-)  
83    
84    
85    
# Line 203  following experimental devices: Line 108  following experimental devices:
108          characters to the controlling terminal          characters to the controlling terminal
109          and receiving keypresses.          and receiving keypresses.
110          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_cons.c</tt></font>          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_cons.c</tt></font>
111            <p>Include file:&nbsp;&nbsp;<font color="#0000f0"><tt>dev_cons.h</tt></font>
112          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x10000000</font>          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x10000000</font>
113      </td>      </td>
114      <td align="left" valign="top" width="25">&nbsp;</td>      <td align="left" valign="top" width="25">&nbsp;</td>
# Line 238  following experimental devices: Line 144  following experimental devices:
144          <p>This device controls the behaviour of CPUs in an emulated          <p>This device controls the behaviour of CPUs in an emulated
145          multi-processor system.          multi-processor system.
146          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_mp.c</tt></font>          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_mp.c</tt></font>
147            <p>Include file:&nbsp;&nbsp;<font color="#0000f0"><tt>dev_mp.h</tt></font>
148          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x11000000</font>          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x11000000</font>
149      </td>      </td>
150      <td></td>      <td></td>
# Line 271  following experimental devices: Line 178  following experimental devices:
178            <tr>            <tr>
179              <td align="left" valign="top"><tt>0x0040</tt></td>              <td align="left" valign="top"><tt>0x0040</tt></td>
180              <td align="left" valign="top">Write: <b><tt>pause_addr(addr)</tt></b>.              <td align="left" valign="top">Write: <b><tt>pause_addr(addr)</tt></b>.
181                  Sets the pause address. (TODO: This is not                  Sets the pause address. (NOTE: This is not
182                  used anymore?)</td>                  used anymore.)</td>
183            </tr>            </tr>
184            <tr>            <tr>
185              <td align="left" valign="top"><tt>0x0050</tt></td>              <td align="left" valign="top"><tt>0x0050</tt></td>
186              <td align="left" valign="top">Write: <b><tt>pause_cpu(i)</tt></b>.              <td align="left" valign="top">Write: <b><tt>pause_cpu(i)</tt></b>.
187                  Stops all CPUs <i>except</i> CPU i.</td>                  Pauses all CPUs <i>except</i> CPU i.</td>
188            </tr>            </tr>
189            <tr>            <tr>
190              <td align="left" valign="top"><tt>0x0060</tt></td>              <td align="left" valign="top"><tt>0x0060</tt></td>
191              <td align="left" valign="top">Write: <b><tt>unpause_cpu(i)</tt></b>.              <td align="left" valign="top">Write: <b><tt>unpause_cpu(i)</tt></b>.
192                  Unpauses all CPUs <i>except</i> CPU i.</td>                  Unpauses CPU i.</td>
193            </tr>            </tr>
194            <tr>            <tr>
195              <td align="left" valign="top"><tt>0x0070</tt></td>              <td align="left" valign="top"><tt>0x0070</tt></td>
# Line 313  following experimental devices: Line 220  following experimental devices:
220                  the specified one.</td>                  the specified one.</td>
221            </tr>            </tr>
222            <tr>            <tr>
223              <td align="left" valign="top">0x00c0</tt></td>              <td align="left" valign="top"><tt>0x00c0</tt></td>
224              <td align="left" valign="top">Read: <b><tt>ipi_read()</tt></b>.              <td align="left" valign="top">Read: <b><tt>ipi_read()</tt></b>.
225                  Returns the next pending IPI. 0 is returned if there is no                  Returns the next pending IPI. 0 is returned if there is no
226                  pending IPI (so 0 shouldn't be used for valid IPIs).                  pending IPI (so 0 shouldn't be used for valid IPIs).
# Line 322  following experimental devices: Line 229  following experimental devices:
229                  Clears the IPI queue, discarding any pending IPIs.</td>                  Clears the IPI queue, discarding any pending IPIs.</td>
230            </tr>            </tr>
231            <tr>            <tr>
232              <td align="left" valign="top">0x00d0</tt></td>              <td align="left" valign="top"><tt>0x00d0</tt></td>
233              <td align="left" valign="top">Read: <b><tt>ncycles()</tt></b>.              <td align="left" valign="top">Read: <b><tt>ncycles()</tt></b>.
234                  Returns approximately the number of cycles executed.                  Returns approximately the number of cycles executed.
235                  Note: this value is not updated for every instruction,                  Note: this value is not updated for every instruction,
# Line 342  following experimental devices: Line 249  following experimental devices:
249          <p>A simple linear framebuffer, for graphics output.          <p>A simple linear framebuffer, for graphics output.
250          640 x 480 pixels, 3 bytes per pixel (red, green, blue, 8 bits each).          640 x 480 pixels, 3 bytes per pixel (red, green, blue, 8 bits each).
251          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_fb.c</tt></font>          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_fb.c</tt></font>
252            <p>Include file:&nbsp;&nbsp;<font color="#0000f0"><tt>dev_fb.h</tt></font>
253          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x12000000</font>          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x12000000</font>
254      </td>      </td>
255      <td></td>      <td></td>
# Line 368  following experimental devices: Line 276  following experimental devices:
276      <td align="left" valign="top">      <td align="left" valign="top">
277          <a name="expdevices_disk"><b><tt>disk</tt>:</b></a>          <a name="expdevices_disk"><b><tt>disk</tt>:</b></a>
278          <p>Disk controller, which can read from and write          <p>Disk controller, which can read from and write
279          to disk images. It does not use interrupts; read and          to emulated IDE disks. It does not use interrupts; read and
280          write operations finish instantaneously.          write operations finish instantaneously.
281          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_disk.c</tt></font>          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_disk.c</tt></font>
282            <p>Include file:&nbsp;&nbsp;<font color="#0000f0"><tt>dev_disk.h</tt></font>
283          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x13000000</font>          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x13000000</font>
284      </td>      </td>
285      <td></td>      <td></td>
# Line 387  following experimental devices: Line 296  following experimental devices:
296            </tr>            </tr>
297            <tr>            <tr>
298              <td align="left" valign="top"><tt>0x0010</tt></td>              <td align="left" valign="top"><tt>0x0010</tt></td>
299              <td align="left" valign="top">Write: Select the SCSI ID to be used in the next              <td align="left" valign="top">Write: Select the IDE ID to be used in the next
300                  read/write operation.</td>                  read/write operation.</td>
301            </tr>            </tr>
302            <tr>            <tr>
# Line 419  following experimental devices: Line 328  following experimental devices:
328          <p>A simple ethernet controller, enough to send          <p>A simple ethernet controller, enough to send
329          and receive packets on a simulated network.          and receive packets on a simulated network.
330          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_ether.c</tt></font>          <p>Source code:&nbsp;&nbsp;<font color="#0000f0"><tt>src/devices/dev_ether.c</tt></font>
331            <p>Include file:&nbsp;&nbsp;<font color="#0000f0"><tt>dev_ether.h</tt></font>
332          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x14000000</font>          <br>Default physical address:&nbsp&nbsp;<font color="#0000f0">0x14000000</font>
333      </td>      </td>
334      <td></td>      <td></td>
# Line 470  means that it can be accessed at virtual Line 380  means that it can be accessed at virtual
380  <tt>0xffffffff90000000</tt> too, but devices should usually be accessed in  <tt>0xffffffff90000000</tt> too, but devices should usually be accessed in
381  a non-cached manner.)  a non-cached manner.)
382    
383  <p> (When using the PPC test machine (<tt>testppc</tt>), the addresses are  <p>When using the Alpha, ARM, or PPC test machines, the addresses are
384  <tt>0x10000000</tt>, <tt>0x11000000</tt> etc., so no need to add any  <tt>0x10000000</tt>, <tt>0x11000000</tt> etc., so no need to add any
385  virtual displacement.)  virtual displacement.
386    
387  <p>The <b><tt>mp</tt></b>, <b><tt>disk</tt></b>, and <b><tt>ether</tt></b>  <p>The <tt>mp</tt>, <tt>disk</tt>, and <tt>ether</tt> devices are agnostic
388  devices are agnostic when it comes to word-length. For example, when  when it comes to word-length. For example, when reading offset
389  reading offset <tt>0x0000</tt> of the <b><tt>mp</tt></b>  <tt>0x0000</tt> of the <tt>mp</tt> device, you may use any kind of read
390  device, you may use any kind of read (an 8-bit read will work just as well  (an 8-bit read will work just as well as a 64-bit read, although the value
391  as a 64-bit read, although the value will be truncated to 8 bits in the  will be truncated to 8 bits in the first case). You can <i>not</i>,
392  first case). You can <i>not</i>, however, read one byte from <tt>0x0000</tt>  however, read one byte from <tt>0x0000</tt> and one from <tt>0x0001</tt>,
393  and one from <tt>0x0001</tt>, and combine the result. The read from  and combine the result. The read from <tt>0x0001</tt> will be invalid.
 <tt>0x0001</tt> will be invalid.  
394    
395  <p>The <b><tt>cons</tt></b> device should be accessed using 8-bit reads  <p>The <tt>cons</tt> device should be accessed using 8-bit reads
396  and writes. Doing a getchar() (ie reading from offset <tt>0x00</tt>)    and writes. Doing a getchar() (ie reading from offset <tt>0x00</tt>)  
397  returns <tt>0</tt> if no character was available.  returns <tt>0</tt> if no character was available. Whenever a character is
398    available, the <tt>cons</tt> device' interrupt is asserted. When there are
399    no more available characters, the interrupt is deasserted. (Remember that
400    the interrupt has to be unmasked to be able to actually cause an
401    interrupt.)
402    
403    <p>IPIs (inter-processor interrupts) are controlled by the <tt>mp</tt>
404    device. Whenever an IPI is "sent" from a source to one or more target
405    CPUs, the interrupt is asserted on the target CPUs, and the IPI number is
406    added last in the IPI queue for each of the target CPUs. It is then up to
407    those CPUs to individually read from offset <tt>0x00c0</tt>, to figure out
408    what kind of IPI it was.
409    
 <p>On MIPS, the <b><tt>cons</tt></b> device is hardwired to interrupt 2  
 (the lowest hardware interrupt). Whenever a character is available, the  
 interrupt is asserted. When there are no more available characters, the  
 interrupt is deasserted. (Remember that the interrupt has to be enabled in  
 the status register of the system coprocessor.)  
   
 <p>The <b><tt>ether</tt></b> device is hardwired to interrupt 3.  
   
 <p>The IPIs controlled by the <b><tt>mp</tt></b> device are hardwired to  
 interrupt 6. Whenever an IPI is "sent", interrupt 6 is asserted on the  
 target CPU(s), and the IPI number is added last in the IPI queue for that  
 CPU. It is then up to that CPU to read from offset <tt>0x00c0</tt>, to  
 figure out what kind of IPI it was.  
   
 <p>A simple tutorial on how to use the <tt>disk</tt> device, if not clear  
 from the description above, can be found here: <a  
 href="test_disk.c"><tt>test_disk.c</tt></a>  
410    
411    
412    <p>Interrupt mappings are as follows:
413    
414    <p><center>
415    <table border="1">
416            <tr><td align="center">
417                    <b><tt>testmips</tt></b>
418            </td></tr>
419            <tr><td>
420                    <table border="0">
421                    <tr><td align="center">IRQ:</td><td>&nbsp;</td>
422                            <td>Used for:</td></tr>
423                    <tr><td align="center">7</td><td></td>
424                            <td>MIPS count/compare interrupt</td></tr>
425                    <tr><td align="center">6</td><td></td>
426                            <td><tt>mp</tt> (inter-processor interrupts)</td></tr>
427                    <tr><td align="center">3</td><td></td>
428                            <td><tt>ether</tt></td></tr>
429                    <tr><td align="center">2</td><td></td>
430                            <td><tt>cons</tt></td></tr>
431                    </table>
432            </td></tr>
433    </table>
434    </center>
435    
436    <p>Other machines:  TODO
437    
438    
439    <p><br>
440    
441    
442    
443  </p>  </p>
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