Using SCODB

Dumping memory

Use the memory dump commands to dump memory:

   d address/dl address                            /* Dump memory as longs */
   db address                                      /* Dump memory as bytes */
   ds address                                      /* Dump memory as shorts */
   dn address                                      /* Dump memory as symbols */

If an address is given that is known by SCODB to be a structure or union, it automatically dumps it member by member; this is further described in ``Structure members''. This can be overridden by typecasting the address to (char *). For example:

   debug0:1> d (char *)&u

The d commands are used to examine memory contents. Depending on the mode of the d command selected, memory is shown grouped as bytes, shorts, or longs.

The ASCII value of each byte is displayed on the right of the screen, with a period (.) denoting a non-printable character or white space, as in hd(C). Note that the bytes are displayed in the ASCII dump from low to high memory, while the memory dump displays memory in possibly larger memory groups which are byte-reversed.

After each line of memory is displayed, the user may move around the dump using the the following vi(C) movement keys: <j>, <k>, <Ctrl><u>, and <Ctrl><d>. The <Space> and <Return> keys are equivalent to j in that they display the next line.

Some examples of dumping memory:

   debug0:2> d &init_tbl
   init_tbl      D0089368 D009C544 D007E09C D0085CBC             h...D..........
   init_tbl+10   D0083F3C D008265C D00863A8 D00826C8             <?.....c...&..
   ...
   debug0:3> ds &dmapage
   dmapage       0087 0083 0081 0082 0000 008B 0089 008A         ................
   ...
   debug0:4> db &maptab
   maptab+60     00 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F .ABCDEFGHIJKLMNO
   maptab+70     50 51 52 53 54 55 56 57 58 59 5A 00 00 00 00 00 PQRSTUVWXYZ.....
   ...
   debug0:5> dn &u+d00
   u+D00          selwait 0000011A u+E34 sysent+2B8
   ...

When dumping the u-page stack using the dn command, the frame pointers appear highlighted in reverse video if a stack backtrace command (b or stack) was previously executed.