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0fd800b245
This patch introduces new probes to check whether the kernel supports
instruction set extensions v2 and v3. The first introduced eBPF
instructions BPF_J{LT,LE,SLT,SLE} in commit 92b31a9af7 ("bpf: add
BPF_J{LT,LE,SLT,SLE} instructions"). The second introduces 32-bit
variants of all jump instructions in commit 092ed0968b ("bpf:
verifier support JMP32").
These probes are useful for userspace BPF projects that want to use newer
instruction set extensions on newer kernels, to reduce the programs'
sizes or their complexity. LLVM already provides an mcpu=probe option to
automatically probe the kernel and select the newest-supported
instruction set extension. That is however not flexible enough for all
use cases. For example, in Cilium, we only want to use the v3
instruction set extension on v5.10+, even though it is supported on all
kernels v5.1+.
Signed-off-by: Paul Chaignon <paul@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/3bfedcd9898c1f41ac67ca61f144fec84c6c3a92.1641314075.git.paul@isovalent.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.