287d6070ac
Currently there are some variables in the purgatory (e.g. kernel_entry) which are defined twice, once in assembler- and once in c-code. The reason for this is that these variables are set during purgatory load, where sanity checks on the corresponding Elf_Sym's are made, while they are used in assembler-code. Thus adding a second definition in c-code is a handy workaround to guarantee correct Elf_Sym's are created. When the purgatory is compiled with -fcommon (default for gcc on s390) this is no problem because both symbols are merged by the linker. However this is not required by ISO C and when the purgatory is built with -fno-common the linker fails with errors like arch/s390/purgatory/purgatory.o:(.bss+0x18): multiple definition of `kernel_entry' arch/s390/purgatory/head.o:/.../arch/s390/purgatory/head.S:230: first defined here Thus remove the duplicate definitions and add the required size and type information to the assembler definition. Also add -fno-common to the command line options to prevent similar hacks in the future. Signed-off-by: Philipp Rudo <prudo@linux.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.