/[gxemul]/trunk/doc/technical.html
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revision 14 by dpavlin, Mon Oct 8 16:18:51 2007 UTC revision 22 by dpavlin, Mon Oct 8 16:19:37 2007 UTC
# Line 4  Line 4 
4  <table border=0 width=100% bgcolor="#d0d0d0"><tr>  <table border=0 width=100% bgcolor="#d0d0d0"><tr>
5  <td width=100% align=center valign=center><table border=0 width=100%><tr>  <td width=100% align=center valign=center><table border=0 width=100%><tr>
6  <td align="left" valign=center bgcolor="#d0efff"><font color="#6060e0" size="6">  <td align="left" valign=center bgcolor="#d0efff"><font color="#6060e0" size="6">
7  <b>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;</b></font>  <b>Gavare's eXperimental Emulator:</b></font><br>
8  <font color="#000000" size="6"><b>Technical details</b>  <font color="#000000" size="6"><b>Technical details</b>
9  </font></td></tr></table></td></tr></table><p>  </font></td></tr></table></td></tr></table><p>
10    
11  <!--  <!--
12    
13  $Id: technical.html,v 1.63 2005/10/07 15:10:00 debug Exp $  $Id: technical.html,v 1.72 2006/02/18 15:18:15 debug Exp $
14    
15  Copyright (C) 2004-2005  Anders Gavare.  All rights reserved.  Copyright (C) 2004-2006  Anders Gavare.  All rights reserved.
16    
17  Redistribution and use in source and binary forms, with or without  Redistribution and use in source and binary forms, with or without
18  modification, are permitted provided that the following conditions are met:  modification, are permitted provided that the following conditions are met:
# Line 108  different kinds of emulation, so these m Line 108  different kinds of emulation, so these m
108          line option.)          line option.)
109    <p>    <p>
110    <li><b>All other modes:</b><br>    <li><b>All other modes:</b><br>
111          These use a kind of dynamic translation system. (This system does          These use a kind of dynamic translation system. This system does
112          not use host-specific backends, so it is not "recompilation" or          not recompile anything into native code, it only uses tables of
113          anything like that.) Speed is slower than real binary translation,          pointers to functions written in (sometimes machine-generated) C
114          but faster than traditional interpretation, and with some tricks          code. Speed is lower than what can be achieved using real binary
115          it will hopefully still give reasonable speed. ARM emulation uses          translation into native code, but higher than when traditional
116          this kind of translation, for example.          interpretation is used. With some tricks, it will hopefully still
117            give reasonable speed. The ARM and PowerPC
118            emulation modes use this kind of translation.
119  </ul>  </ul>
120    
121    
# Line 318  a CDROM ISO image. You can use a read-wr Line 320  a CDROM ISO image. You can use a read-wr
320  files in both directions, but then you should be aware of the  files in both directions, but then you should be aware of the
321  fragmentation issue mentioned above.  fragmentation issue mentioned above.
322    
 <p>TODO: Write a section on how to connect multiple emulator instances.  
 (Using the <tt>local_port</tt> and <tt>add_remote</tt> configuration file  
 commands.)  
323    
324    
325    
# Line 331  commands.) Line 330  commands.)
330  <a name="devices"></a>  <a name="devices"></a>
331  <h3>Emulation of hardware devices</h3>  <h3>Emulation of hardware devices</h3>
332    
333  Each file in the <tt>src/device/</tt> directory is responsible for one  Each file called <tt>dev_*.c</tt> in the <tt>src/device/</tt> directory is
334  hardware device. These are used from <tt>src/machine.c</tt>, when  responsible for one hardware device. These are used from
335  initializing which hardware a particular machine model will be using, or  <tt>src/machines/machine_*.c</tt>, when initializing which hardware a particular
336  when adding devices to a machine using the <tt>device()</tt> command in  machine model will be using, or when adding devices to a machine using the
337  configuration files.  <tt>device()</tt> command in configuration files.
   
 <p><font color="#ff0000">NOTE: The device registry subsystem is currently  
 in a state of flux, as it is being redesigned.</font>  
338    
339  <p>(I'll be using the name "<tt>foo</tt>" as the name of the device in all  <p>(I'll be using the name "<tt>foo</tt>" as the name of the device in all
340  these examples.  This is pseudo code, it might need some modification to  these examples.  This is pseudo code, it might need some modification to
# Line 351  actually compile and run.) Line 347  actually compile and run.)
347    <li>A <tt>devinit</tt> function in <tt>src/devices/dev_foo.c</tt>. It    <li>A <tt>devinit</tt> function in <tt>src/devices/dev_foo.c</tt>. It
348          would typically look something like this:          would typically look something like this:
349  <pre>  <pre>
350          /*          DEVINIT(foo)
          *  devinit_foo():  
          */  
         int devinit_foo(struct devinit *devinit)  
351          {          {
352                  struct foo_data *d = malloc(sizeof(struct foo_data));                  struct foo_data *d = malloc(sizeof(struct foo_data));
353    
# Line 362  actually compile and run.) Line 355  actually compile and run.)
355                          fprintf(stderr, "out of memory\n");                          fprintf(stderr, "out of memory\n");
356                          exit(1);                          exit(1);
357                  }                  }
358                  memset(d, 0, sizeof(struct foon_data));                  memset(d, 0, sizeof(struct foo_data));
359    
360                  /*                  /*
361                   *  Set up stuff here, for example fill d with useful                   *  Set up stuff here, for example fill d with useful
# Line 374  actually compile and run.) Line 367  actually compile and run.)
367                    
368                  memory_device_register(devinit->machine->memory, devinit->name,                  memory_device_register(devinit->machine->memory, devinit->name,
369                      devinit->addr, DEV_FOO_LENGTH,                      devinit->addr, DEV_FOO_LENGTH,
370                      dev_foo_access, (void *)d, MEM_DEFAULT, NULL);                      dev_foo_access, (void *)d, DM_DEFAULT, NULL);
371                    
372                  /*  This should only be here if the device                  /*  This should only be here if the device
373                      has a tick function:  */                      has a tick function:  */
# Line 386  actually compile and run.) Line 379  actually compile and run.)
379          }                }      
380  </pre><br>  </pre><br>
381    
382            <p><tt>DEVINIT(foo)</tt> is defined as <tt>int devinit_foo(struct devinit *devinit)</tt>,
383            and the <tt>devinit</tt> argument contains everything that the device driver's
384            initialization function needs.
385    
386      <p>
387    <li>At the top of <tt>dev_foo.c</tt>, the <tt>foo_data</tt> struct    <li>At the top of <tt>dev_foo.c</tt>, the <tt>foo_data</tt> struct
388          should be defined.          should be defined.
389  <pre>  <pre>
# Line 394  actually compile and run.) Line 392  actually compile and run.)
392                  /*  ...  */                  /*  ...  */
393          }          }
394  </pre><br>  </pre><br>
395            (There is an exception to this rule; ugly hacks which allow
396            code in <tt>src/machine.c</tt> to use some structures makes it
397            necessary to place the <tt>struct foo_data</tt> in
398            <tt>src/include/devices.h</tt> instead of in <tt>dev_foo.c</tt>
399            itself. This is useful for example for interrupt controllers.)
400      <p>
401    <li>If <tt>foo</tt> has a tick function (that is, something that needs to be    <li>If <tt>foo</tt> has a tick function (that is, something that needs to be
402          run at regular intervals) then <tt>FOO_TICKSHIFT</tt> and a tick          run at regular intervals) then <tt>FOO_TICKSHIFT</tt> and a tick
403          function need to be defined as well:          function need to be defined as well:
404  <pre>  <pre>
405          #define FOO_TICKSHIFT           10          #define FOO_TICKSHIFT           14
406    
407          void dev_foo_tick(struct cpu *cpu, void *extra)          void dev_foo_tick(struct cpu *cpu, void *extra)
408          {          {
# Line 412  actually compile and run.) Line 415  actually compile and run.)
415          }          }
416  </pre><br>  </pre><br>
417    
418      <li>Does this device belong to a standard bus?
419            <ul>
420              <li>If this device should be detectable as a PCI device, then
421                    glue code should be added to
422                    <tt>src/devices/bus_pci.c</tt>.
423              <li>If this is a legacy ISA device which should be usable by
424                    any machine which has an ISA bus, then the device should
425                    be added to <tt>src/devices/bus_isa.c</tt>.
426            </ul>
427      <p>
428    <li>And last but not least, the device should have an access function.    <li>And last but not least, the device should have an access function.
429          The access function is called whenever there is a load or store          The access function is called whenever there is a load or store
430          to an address which is in the device' memory mapped region.          to an address which is in the device' memory mapped region. To
431  <pre>          simplify things a little, a macro <tt>DEVICE_ACCESS(x)</tt>
432          int dev_foo_access(struct cpu *cpu, struct memory *mem,          is expanded into<pre>
433            int dev_x_access(struct cpu *cpu, struct memory *mem,
434              uint64_t relative_addr, unsigned char *data, size_t len,              uint64_t relative_addr, unsigned char *data, size_t len,
435              int writeflag, void *extra)              int writeflag, void *extra)
436    </pre>  The access function can look like this:
437    <pre>
438            DEVICE_ACCESS(foo)
439          {          {
440                  struct foo_data *d = extra;                  struct foo_data *d = extra;
441                  uint64_t idata = 0, odata = 0;                  uint64_t idata = 0, odata = 0;
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