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[/] [openrisc/] [trunk/] [gnu-old/] [gdb-6.8/] [sim/] [ppc/] [hw_vm.c] - Blame information for rev 856

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1 24 jeremybenn
/*  This file is part of the program psim.
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    Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>
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    This program is free software; you can redistribute it and/or modify
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    it under the terms of the GNU General Public License as published by
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    the Free Software Foundation; either version 2 of the License, or
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    (at your option) any later version.
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    This program is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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    GNU General Public License for more details.
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    You should have received a copy of the GNU General Public License
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    along with this program; if not, write to the Free Software
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    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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    */
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#ifndef _HW_VM_C_
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#define _HW_VM_C_
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#include "device_table.h"
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#include "cpu.h"
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#include <signal.h>
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/* DEVICE
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   vm - virtual memory device for user simulation modes
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   DESCRIPTION
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   In user mode, mapped text, data and stack addresses are managed by
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   the core.  Unmapped addresses are passed onto this device (because
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   it establishes its self as the fallback device) for processing.
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   During initialization, children of this device will request the
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   mapping of the initial text and data segments.  Those requests are
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   passed onto the core device so that that may establish the initial
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   memory regions.
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   Once the simulation has started (as noted above) any access to an
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   unmapped address range will be passed down to this device as an IO
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   access.  This device will then either attach additional memory to
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   the core device or signal the access as being invalid.
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   The IOCTL function is used to notify this device of any changes to
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   the users `brk' point.
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   PROPERTIES
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   stack-base = <number>
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   Specifies the lower address of the stack segment in the users
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   virtual address space.  The initial stack page is defined by
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   stack-base + nr-bytes.
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   nr-bytes = <number>
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   Specifies the maximum size of the stack segment in the users
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   address space.
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   */
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typedef struct _hw_vm_device {
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  /* area of memory valid for stack addresses */
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  unsigned_word stack_base; /* min possible stack value */
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  unsigned_word stack_bound;
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  unsigned_word stack_lower_limit;
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  /* area of memory valid for heap addresses */
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  unsigned_word heap_base;
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  unsigned_word heap_bound;
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  unsigned_word heap_upper_limit;
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} hw_vm_device;
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static void
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hw_vm_init_address_callback(device *me)
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{
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  hw_vm_device *vm = (hw_vm_device*)device_data(me);
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  /* revert the stack/heap variables to their defaults */
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  vm->stack_base = device_find_integer_property(me, "stack-base");
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  vm->stack_bound = (vm->stack_base
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                     + device_find_integer_property(me, "nr-bytes"));
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  vm->stack_lower_limit = vm->stack_bound;
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  vm->heap_base = 0;
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  vm->heap_bound = 0;
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  vm->heap_upper_limit = 0;
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  /* establish this device as the default memory handler */
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  device_attach_address(device_parent(me),
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                        attach_callback + 1,
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                        (((unsigned)0)-1) /*nr_bytes - ignore*/,
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                        access_read_write /*access*/,
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                        me);
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}
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static void
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hw_vm_attach_address(device *me,
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                     attach_type attach,
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                     int space,
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                     unsigned_word addr,
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                     unsigned nr_bytes,
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                     access_type access,
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                     device *client) /*callback/default*/
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{
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  hw_vm_device *vm = (hw_vm_device*)device_data(me);
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  /* update end of bss if necessary */
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  if (vm->heap_base < addr + nr_bytes) {
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    vm->heap_base = addr + nr_bytes;
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    vm->heap_bound = addr + nr_bytes;
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    vm->heap_upper_limit = addr + nr_bytes;
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  }
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  device_attach_address(device_parent(me),
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                        attach_raw_memory,
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                        addr,
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                        nr_bytes,
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                        access,
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                        me);
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}
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static unsigned
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hw_vm_add_space(device *me,
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                unsigned_word addr,
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                unsigned nr_bytes,
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                cpu *processor,
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                unsigned_word cia)
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{
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  hw_vm_device *vm = (hw_vm_device*)device_data(me);
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  unsigned_word block_addr;
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  unsigned block_nr_bytes;
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  /* an address in the stack area, allocate just down to the addressed
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     page */
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  if (addr >= vm->stack_base && addr < vm->stack_lower_limit) {
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    block_addr = FLOOR_PAGE(addr);
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    block_nr_bytes = vm->stack_lower_limit - block_addr;
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    vm->stack_lower_limit = block_addr;
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  }
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  /* an address in the heap area, allocate all of the required heap */
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  else if (addr >= vm->heap_upper_limit && addr < vm->heap_bound) {
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    block_addr = vm->heap_upper_limit;
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    block_nr_bytes = vm->heap_bound - vm->heap_upper_limit;
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    vm->heap_upper_limit = vm->heap_bound;
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  }
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  /* oops - an invalid address - abort the cpu */
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  else if (processor != NULL) {
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    cpu_halt(processor, cia, was_signalled, SIGSEGV);
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    return 0;
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  }
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  /* 2*oops - an invalid address and no processor */
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  else {
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    return 0;
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  }
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  /* got the parameters, allocate the space */
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  device_attach_address(device_parent(me),
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                        attach_raw_memory,
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                        block_addr,
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                        block_nr_bytes,
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                        access_read_write,
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                        me);
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  return block_nr_bytes;
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}
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static unsigned
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hw_vm_io_read_buffer_callback(device *me,
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                           void *dest,
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                           int space,
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                           unsigned_word addr,
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                           unsigned nr_bytes,
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                           cpu *processor,
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                           unsigned_word cia)
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{
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  if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {
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    memset(dest, 0, nr_bytes); /* always initialized to zero */
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    return nr_bytes;
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  }
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  else
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    return 0;
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}
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static unsigned
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hw_vm_io_write_buffer_callback(device *me,
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                            const void *source,
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                            int space,
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                            unsigned_word addr,
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                            unsigned nr_bytes,
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                            cpu *processor,
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                            unsigned_word cia)
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{
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  if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {
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    return device_dma_write_buffer(device_parent(me), source,
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                                   space, addr,
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                                   nr_bytes,
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                                   0/*violate_read_only*/);
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  }
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  else
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    return 0;
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}
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static int
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hw_vm_ioctl(device *me,
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            cpu *processor,
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            unsigned_word cia,
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            device_ioctl_request request,
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            va_list ap)
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{
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  /* While the caller is notified that the heap has grown by the
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     requested amount, the heap is actually extended out to a page
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     boundary. */
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  hw_vm_device *vm = (hw_vm_device*)device_data(me);
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  switch (request) {
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  case device_ioctl_break:
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    {
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      unsigned_word requested_break = va_arg(ap, unsigned_word);
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      unsigned_word new_break = ALIGN_8(requested_break);
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      unsigned_word old_break = vm->heap_bound;
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      signed_word delta = new_break - old_break;
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      if (delta > 0)
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        vm->heap_bound = ALIGN_PAGE(new_break);
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      break;
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    }
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  default:
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    device_error(me, "Unsupported ioctl request");
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    break;
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  }
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  return 0;
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}
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static device_callbacks const hw_vm_callbacks = {
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  { hw_vm_init_address_callback, },
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  { hw_vm_attach_address,
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    passthrough_device_address_detach, },
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  { hw_vm_io_read_buffer_callback,
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    hw_vm_io_write_buffer_callback, },
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  { NULL, passthrough_device_dma_write_buffer, },
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  { NULL, }, /* interrupt */
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  { generic_device_unit_decode,
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    generic_device_unit_encode, },
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  NULL, /* instance */
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  hw_vm_ioctl,
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};
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static void *
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hw_vm_create(const char *name,
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             const device_unit *address,
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             const char *args)
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{
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  hw_vm_device *vm = ZALLOC(hw_vm_device);
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  return vm;
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}
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const device_descriptor hw_vm_device_descriptor[] = {
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  { "vm", hw_vm_create, &hw_vm_callbacks },
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  { NULL },
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};
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#endif /* _HW_VM_C_ */

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