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e0491f6479
When literal pool size exceeds 512k, it's no longer possible to reference all the entries in it using a single base register and long displacement. Therefore, PC-relative lgfrl and lgrl instructions need to be used. Unfortunately, they require their arguments to be aligned to 4- and 8-byte boundaries respectively. This generates certain overhead due to necessary padding bytes. Grouping 4- and 8-byte entries together reduces the maximum overhead to 6 bytes (2 for aligning 4-byte entries and 4 for aligning 8-byte entries). While in theory it is possible to detect whether or not alignment is needed by comparing the literal pool size with 512k, in practice this leads to having two ways of emitting constants, making the code more complicated. Prefer code simplicity over trivial size saving, and always group and align literal pool entries. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191118180340.68373-3-iii@linux.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.
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.