mdb_printf()

void mdb_printf(const char *format, ...);

Print formatted output using the specified format string and arguments. Module writers should use mdb_printf() for all output, except for warning and error messages. This function automatically triggers the built-in output pager when appropriate. The mdb_printf() function is similar to printf(3C), with certain exceptions: the %C, %S, and %ws specifiers for wide character strings are not supported, the %f floating-point format is not supported, the %e, %E, %g, and %G specifiers for alternative double formats produce only a single style of output, and precision specifications of the form %.n are not supported. The list of specifiers that are supported follows:

Flag Specifiers

%#

If the # sign is found in the format string, this selects the alternate form of the given format. Not all formats have an alternate form; the alternate form is different depending on the format. Refer to the format descriptions below for details on the alternate format.

%+

When printing signed values, always display the sign (prefix with either '+' or '-'). Without %+, positive values have no sign prefix, and negative values have a '-' prefix prepended to them.

%-

Left-justify the output within the specified field width. If the width of the output is less than the specified field width, the output will be padded with blanks on the right-hand side. Without %-, values are right-justified by default.

%0

Zero-fill the output field if the output is right-justified and the width of the output is less than the specified field width. Without %0, right-justified values are prepended with blanks in order to fill the field.

Field Width Specifiers

%n

Field width is set to the specified decimal value.

%?

Field width is set to the maximum width of a hexadecimal pointer value. This is 8 in an ILP32 environment, and 16 in an LP64 environment.

%*

Field width is set to the value specified at the current position in the argument list. This value is assumed to be an int. Note that in the 64-bit compilation environment, it may be necessary to cast long values to int.

Integer Specifiers

%h

Integer value to be printed is a short.

%l

Integer value to be printed is a long.

%ll

Integer value to be printed is a long long.

Terminal Attribute Specifiers

If standard output for the debugger is a terminal, and terminal attributes can be obtained by the terminfo database, the following terminal escape constructs can be used:

%<n>

Enable the terminal attribute corresponding to n. Only a single attribute can be enabled with each instance of %<>.

%</n>

Disable the terminal attribute corresponding to n. Note that in the case of reverse video, dim text, and bold text, the terminal codes to disable these attributes might be identical. Therefore, it might not be possible to disable these attributes independently of one another.

If no terminal information is available, each terminal attribute construct is ignored by mdb_printf(). For more information on terminal attributes, see terminfo(4). The available terminfo attributes are:

a

Alternate character set

b

Bold text

d

Dim text

r

Reverse video

s

Best standout capability

u

Underlining

Format Specifiers

%%

The '%' symbol is printed.

%a

Prints an address in symbolic form. The minimum size of the value associated with %a is a uintptr_t; specifying %la is not necessary. If address-to-symbol conversion is on, the debugger will attempt to convert the address to a symbol name followed by an offset in the current output radix and print this string; otherwise, the value is printed in the default output radix. If %#a is used, the alternate format adds a ':' suffix to the output.

%A

This format is identical to %a, except when an address cannot be converted to a symbol name plus an offset, nothing is printed. If %#A is used, the alternate format prints a '?' when address conversion fails.

%b

Decode and print a bit field in symbolic form. This specifier expects two consecutive arguments: the bit field value (int for %b, long for %lb, and so forth), and a pointer to an array of mdb_bitmask_t structures:

typedef struct mdb_bitmask {
		const char *bm_name;       /* String name to print */
		u_longlong_t bm_mask;      /* Mask for bits */
		u_longlong_t bm_bits;      /* Result for value & mask */
} mdb_bitmask_t;

The array should be terminated by a structure whose bm_name field is set to NULL. When %b is used, the debugger reads the value argument, then iterates through each mdb_bitmask structure checking to see if:

(value & bitmask->bm_mask) == bitmask->bm_bits

If this expression is true, the bm_name string is printed. Each string printed is separated by a comma. The following example shows how %b can be used to decode the t_flag field in a kthread_t:

const mdb_bitmask_t t_flag_bits[] = {
		{ "T_INTR_THREAD", T_INTR_THREAD, T_INTR_THREAD },
		{ "T_WAKEABLE", T_WAKEABLE, T_WAKEABLE },
		{ "T_TOMASK", T_TOMASK, T_TOMASK },
		{ "T_TALLOCSTK", T_TALLOCSTK, T_TALLOCSTK },
			...
		{ NULL, 0, 0 }
};

void
thr_dump(kthread_t *t)
{
		mdb_printf("t_flag = <%hb>\n", t->t_flag, t_flag_bits);

		...
}

If t_flag was set to 0x000a, the function would print:

t_flag = <T_WAKEABLE,T_TALLOCSTK>

If %#b is specified, the union of all bits that were not matched by an element in the bitmask array is printed as a hexadecimal value following the decoded names.

%c

Print the specified integer as an ASCII character.

%d

Print the specified integer as a signed decimal value. Same as %i. If %#d is specified, the alternate format prefixes the value with '0t'.

%e

Print the specified double in the floating-point format [+/-]d.ddddddde[+/-]dd, where there is one digit before the radix character, seven digits of precision, and at least two digits following the exponent.

%E

Print the specified double using the same rules as %e, except that the exponent character will be 'E' instead of 'e'.

%g

Print the specified double in the same floating-point format as %e, but with sixteen digits of precision. If %llg is specified, the argument is expected to be of type long double (quad-precision floating-point value).

%G

Print the specified double using the same rules as %g, except that the exponent character will be 'E' instead of 'e'.

%i

Print the specified integer as a signed decimal value. Same as %d. If %#i is specified, the alternate format prefixes the value with '0t'.

%I

Print the specified 32-bit unsigned integer as an Internet IPv4 address in dotted-decimal format (for example, the hexadecimal value 0xffffffff would print as 255.255.255.255).

%m

Print a margin of whitespace. If no field is specified, the default output margin width is used; otherwise, the field width determines the number of characters of white space that are printed.

%o

Print the specified integer as an unsigned octal value. If %#o is used, the alternate format prefixes the output with '0'.

%p

Print the specified pointer (void *) as a hexadecimal value.

%q

Print the specified integer as a signed octal value. If %#o is used, the alternate format prefixes the output with '0'.

%r

Print the specified integer as an unsigned value in the current output radix. The user can change the output radix using the $d dcmd. If %#r is specified, the alternate format prefixes the value with the appropriate base prefix: '0i' for binary, '0o' for octal, '0t' for decimal, or '0x' for hexadecimal.

%R

Print the specified integer as a signed value in the current output radix. If %#R is specified, the alternate format prefixes the value with the appropriate base prefix.

%s

Print the specified string (char *). If the string pointer is NULL, the string '<NULL>' is printed.

%t

Advance one or more tab stops. If no width is specified, output advances to the next tab stop; otherwise the field width determines how many tab stops are advanced.

%T

Advance the output column to the next multiple of the field width. If no field width is specified, no action is taken. If the current output column is not a multiple of the field width, white space is added to advance the output column.

%u

Print the specified integer as an unsigned decimal value. If %#u is specified, the alternate format prefixes the value with '0t'.

%x

Print the specified integer as a hexadecimal value. The characters a-f are used as the digits for the values 10-15. If %#x is specified, the alternate format prefixes the value with '0x'.

%X

Print the specified integer as a hexadecimal value. The characters A-F are used as the digits for the values 10-15. If %#X is specified, the alternate format prefixes the value with '0X'.

%Y

The specified time_t is printed as the string 'year month day HH:MM:SS'.