.TH MD 1 "August 4, 2004"
.SH NAME
md, mdWcN, mdr, mds, mm, mmW\- Memory manipulation commands
.SH SYNOPSIS
md [ \fIaddress-expression\fP [ \fIline-count\fP [\fIoutput-radix\fP ] ] ]
.LP
md\fIW\fRc\fIn\fR [ \fIaddress-expression\fP [ \fIline-count\fP [\fIoutput-radix\fP ] ] ]
.LP
mdp \fIphysical-address-expression\fP,\fIbytes\fP
.LP
mdr \fIaddress-expression\fP,\fIbytes\fP
.LP
mds [ \fIaddress-expression\fP [ \fIline-count\fP [\fIoutput-radix\fP ] ] ]
.LP
mm \fIaddress-expression\fP \fInew-contents\fP
.LP
mm\fIW\fR \fIaddress-expression\fP \fInew-contents\fP
.SH DESCRIPTION
The
.B md
command is used to display the contents of memory.
The \fIaddress-expression\fP may be a numeric value (decimal or
hexidecimal), a symbol name, a register name preceeded by one or more
percent symbols '%', an environment variable name preceeded by
a currency symbol '$',  or a simple expression consisting of a
symbol name, an addition or subtraction character and a numeric
value (decimal or hexidecimal).
.P
If an address is specified and the \fIline-count\fP or \fIradix\fP arguments
are omitted, they default to the values of the \fBMDCOUNT\fP and \fBRADIX\fP
environment variables respectively.  If the \fBMDCOUNT\fP or \fBRADIX\fP
environment variables are unset, the appropriate defaults will be used [see
\fBENVIRONMENT\fP below].  If no address is specified then md resumes
after the last address printed, using the previous values of count and
radix.  The start address is rounded down to a multiple of the
BYTESPERWORD (md) or width (md\fIW\fR).
.P
md uses the current value of environment variable \fBBYTESPERWORD\fP to
read the data.  When reading hardware registers that require special
widths, it is more convenient to use md\fIW\fRc\fIn\fR where \fIW\fR is
the width for this command and \fRc\fIn\fR is the number of entries to
read.  For example, md1c20 reads 20 bytes, 1 at a time.  To continue
printing just type md, the width and count apply to following md
commands with no parameters.  \fBNote:\fR The count is the number of
repeats of the width, unlike MDCOUNT which gives the number of md lines
to print.
.P
The
.B mdp
command displays the contents of physical memory, starting at the
specified physical address for the specified number of bytes.
The address is preceded by 'phys'.
.P
The
.B mdr
command displays the raw contents of memory, starting at the specified
address for the specified number of bytes.
The data is printed in one line without a leading address and no
trailing character conversion.
.B mdr
is intended for interfacing with external debuggers, it is of little
use to humans.
.P
The
.B mds
command displays the contents of memory one word per line and
attempts to correlate the contents of each word with a symbol
in the symbol table.   If no symbol is found, the ascii representation
of the word is printed, otherwise the symbol name and offset from
symbol value are printed.
By default the section data is printed for kernel symbols.
.P
The
.B mm
and
\fBmm\fIW\fR
commands allow modification of memory.   The bytes at the address
represented by \fIaddress-expression\fP are changed to
\fInew-contents\fP.  \fInew-contents\fP is allowed to be an
\fIaddress-expression\fP.
.B mm
changes a machine word, \fBmm\fIW\fR changes \fIW\fR bytes at that
address.
.SH LIMITATIONS
None.
.SH ENVIRONMENT
.TP 8
MDCOUNT
This environment variable (default=8) defines the number of lines
that will be displayed by each invocation of the \fBmd\fP command.

.TP 8
RADIX
This environment variable (default=16) defines the radix used to
print the memory contents.

.TP 8
BYTESPERWORD
This environment variable (default=4) selects the width of output
data when printing memory contents.  Select the value two to get
16-bit word output, select the value one to get byte output.

.TP 8
LINES
This environment variable governs the number of lines of output
that will be presented before the kernel debugger built-in pager
pauses the output.   This variable only affects the functioning
of the \fBmd\fP and \fBmds\fP if the \fBMDCOUNT\fP variable
is set to a value greater than the \fBLINES\fP variable.

.TP 8
NOSECT
If the \fBNOSECT\fP environment variable is non-zero then the
section information is suppressed.
The default is NOSECT=1 so section data is suppressed; use set\ NOSECT=0
to see section information.
.SH SMP CONSIDERATIONS
None.
.SH EXAMPLES
.TP 8
md %edx
Display memory starting at the address contained in register \fB%edx\fP.

.TP 8
mds %esp
Display stack contents symbolically.   This command is quite useful
in manual stack traceback.

.TP 8
mm 0xc0252110 0x25
Change the memory location at 0xc0252110 to the value 0x25.

.TP 8
md chrdev_table 15
Display 15 lines (at 16 bytes per line) starting at address
represented by the symbol \fIchrdev_table\fP.