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35 .Nd kernel symbol table interface
41 character device provides a read-only interface to a snapshot of the kernel
43 The in-kernel symbol manager is designed to be able to handle
44 many types of symbols tables, however, only
46 symbol tables are supported by this device.
47 The ELF format image contains two
48 sections: a symbol table and a corresponding string table.
49 .Bl -tag -width indent -offset indent
51 The SYMTAB section contains the symbol table entries present in the current
52 running kernel, including the symbol table entries of any loaded modules.
53 The symbols are ordered by the kernel module load time starting with kernel file
54 symbols first, followed by the first loaded module's symbols and so on.
56 The STRTAB section contains the symbol name strings from the kernel and any
57 loaded modules that the symbol table entries reference.
60 Elf formatted symbol table data read from the
62 file represents the state of the kernel at the time when the device is opened.
65 has no text or data, most of the fields are initialized to NULL.
68 driver does not block the loading or unloading of modules into the kernel
71 file is open but may contain stale data.
73 .Bl -tag -width /dev/ksymsX
84 The device is already open.
87 before it can be opened again.
89 There is a resource shortage in the kernel.
91 The driver was unsuccessful in creating a snapshot of the kernel symbol
93 This may occur if the kernel was in the process of loading or
103 device exists in many different operating systems.
104 This implementation is similar in function to the Solaris and NetBSD
110 driver first appeared in
117 driver was written by
118 .An Stacey Son Aq Mt sson@FreeBSD.org .
120 Because files can be dynamically linked into the kernel at any time the symbol
121 information can vary.
124 file, you have access to an ELF image which represents a snapshot of the state
125 of the kernel symbol information at that instant in time.
126 Keeping the device open does not block the loading or unloading of kernel
128 To get a new snapshot you must close and re-open the device.
130 A process is only allowed to open the
133 The process must close the
135 before it is allowed to open it again.