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35 .Nd kernel symbol table interface
41 character device provides a read-only interface to a snapshot of the kernel
42 symbol table. The in-kernel symbol manager is designed to be able to handle
43 many types of symbols tables, however, only
45 symbol tables are supported by this device. The ELF format image contains two
46 sections: a symbol table and a corresponding string table.
47 .Bl -tag -width indent -offset indent
49 The SYMTAB section contains the symbol table entries present in the current
50 running kernel, including the symbol table entries of any loaded modules. The
51 symbols are ordered by the kernel module load time starting with kernel file
52 symbols first, followed by the first loaded module's symbols and so on.
54 The STRTAB section contains the symbol name strings from the kernel and any
55 loaded modules that the symbol table entries reference.
58 Elf formatted symbol table data read from the
60 file represents the state of the kernel at the time when the device is opened.
63 has no text or data, most of the fields are initialized to NULL.
66 driver does not block the loading or unloading of modules into the kernel
69 file is open but may contain stale data.
73 command codes below are defined in
76 The (third) argument to the
78 should be a pointer to the type indicated.
79 .Bl -tag -width indent -offset indent
80 .It Dv KIOCGSIZE (size_t)
81 Returns the total size of the current symbol table.
82 This can be used when allocating a buffer to make a copy of
83 the kernel symbol table.
84 .It Dv KIOCGADDR (void *)
85 Returns the address of the kernel symbol table mapped in
89 .Bl -tag -width /dev/ksymsX
100 The device is already open. A process must close
102 before it can be opened again.
104 There is a resource shortage in the kernel.
106 The driver was unsuccessful in creating a snapshot of the kernel symbol
107 table. This may occur if the kernel was in the process of loading or
118 device exists in many different operating systems.
119 This implementation is similar in function to the Solaris and NetBSD
125 driver first appeared in
132 driver was written by
133 .An Stacey Son Aq Mt sson@FreeBSD.org .
135 Because files can be dynamically linked into the kernel at any time the symbol
136 information can vary. When you open the
138 file, you have access to an ELF image which represents a snapshot of the state of the kernel symbol information at that instant in time. Keeping the device open does not block the loading or unloading of kernel modules. To get a new snapshot you must close and re-open the device.
140 A process is only allowed to open the
142 file once at a time. The process must close the
144 before it is allowed to open it again.
148 driver uses the calling process' memory address space to store the snapshot.
150 can be used to get the memory address where the symbol table is stored to
153 may also be used but it will map it to another address.