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The kernel provides a __packed definition to abstract away from the compiler specific attributes tag. Convert all packed structures in VSP1 to use it. The GCC documentation [0] describes this attribute as "the structure or union is placed to minimize the memory required". The Keil compiler documentation at [1] warns that the use of this attribute can cause a performance penalty in the event that the compiler can not deduce the allignment of each field. Careful examination of the object code generated both with and without this attribute shows that these structures are accessed identically and are not affected by any performance penalty. The structures are correctly aligned and padded to match the needs of the hardware already. This patch does not serve to make a decision as to the use of the attribute, but purely to clean up the code to use the kernel defined abstraction as per [2]. [0] https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute [1] http://www.keil.com/support/man/docs/armcc/armcc_chr1359124230195.htm [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/compiler-gcc.h?h=v4.16-rc5#n92 Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> |
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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.