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What is symbol in Linux kernel?
In Linux, the System. map file is a symbol table used by the kernel. A symbol table is a look-up between symbol names and their addresses in memory. A symbol name may be the name of a variable or the name of a function.
Under Which version of GPL is the Linux kernel distributed?
Developers can omit it when licensing their software; the Linux kernel, for instance, is licensed under GPLv2 without the “any later version” clause.
Are all kernel modules GPL?
Some would hold that all kernel modules are derived works of the kernel, so have to be GPLed regardless of header inclusion. Alternatively your closed module derives from the GPL module, and the GPL module derives from the kernel, so the closed module has to also be GPL.
What is EXPORT_ SYMBOL_ GPL?
It is macro to define some symbol (e.g. function) as exportable (seen from kernel loadable modules). If the symbol has no “EXPORT_SYMBOL”, it will be not accessible from modules. EXPORT_SYMBOL_GPL will show the symbol only in GPL-licensed modules, and EXPORT_SYMBOL – in modules with any license.
Where is the kernel symbol table?
/proc/ksyms
The symbol table lives in /proc/ksyms .
How do I create a Symver module?
symvers is (re)generated when you (re)compile modules. Run make modules , and you should get a Module. symvers file at the root of the kernel tree. Note that if you only ran make and not make modules , you haven’t built any modules yet.
Is GPL a Linux kernel?
The Linux Kernel is provided under the terms of the GNU General Public License version 2 only (GPL-2.0), as provided in LICENSES/preferred/GPL-2.0, with an explicit syscall exception described in LICENSES/exceptions/Linux-syscall-note, as described in the COPYING file.
Is Linux a GPL?
Which license is released Linux kernel?
GNU General Public License version 2 only
Linux as a whole is released under the GNU General Public License version 2 only (GPL-2.0-only) with an explicit syscall exception (Linux-syscall-note), but it also contains several files under other compatible licenses.
What is Export_symbol in Linux kernel?
EXPORT_SYMBOL() is specific to the Linux kernel. It is used in the translation unit of the definition to make the symbol available to loadable modules. So EXPORT_SYMBOL is just a mechanism like extern, but it’s for reference between loadable modules not file.
What does Vmlinuz stand for?
vmlinuz = Virtual Memory LINUx gZip = Compressed Linux kernel Executable vmlinux = Virtual Memory LINUX = Non-compressed Linux Kernel Executable At the head of this kernel image (vmlinuz) is a routine that does some minimal amount of hardware setup and then decompresses the kernel contained within the kernel image and …
What is Export _ symbol _ GPL in Linux kernel code?
That macro appears many a times in kernel code… It is macro to define some symbol (e.g. function) as exportable (seen from kernel loadable modules). If the symbol has no “EXPORT_SYMBOL”, it will be not accessible from modules. EXPORT_SYMBOL_GPL will show the symbol only in GPL-licensed modules, and EXPORT_SYMBOL – in modules with any license.
Where are the symbols located in the kernel?
You can think of kernel symbols (either functions or data objects) as visible at three different levels in the kernel source code: “exported”, and therefore visible and available to any loadable module. Exporting symbols for modules is typically done with one of: EXPORT_SYMBOL_GPL (), which exports only to GPL-licensed modules.
Why does Linux still use the GPLv2?
Because GPL v2 and v3 are incompatible, it is illegal to release Linux under v3 with any contributions licensed under v2 only. Second, Torvalds personally does not like GPL v3. He particularly dislikes certain provisions (like anti-tivoization), which are not restrictions he wants to impose on users of his software.