Rasmus Villemoes d4011ce0a3 bitbake: bb/utils.py: add break_hardlinks helper
bb.utils.copyfile is called in a few places with identical src and dst
in order to create an st_nlinks==1 version of the file. That that even
works relies on an implementation detail of copyfile (namely, that it
creates a temporary file and then does a rename). Moreover, it's a waste
of time if the file already has st_nlinks==1.

So create a helper that optimizes away the copy in the st_nlinks==1
case. Of course, this helper relies on the same implementation detail,
but that's now contained within bb.utils itself.

To test that we do at least sometimes hit the no-copy path, I tested
locally with

     if sstat[stat.ST_NLINK] == 1:
+        bb.note("Woohoo, 2*%d bytes I/O avoided" % sstat[stat.ST_SIZE])
         return True

(and the obvious places in oe-core patched), and the do_package log files
are indeed filled with woohoo notes.

(Bitbake rev: 7ae93cf40ab91965147055100432961436bce46c)

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2018-08-16 09:50:42 +01:00
2018-02-24 10:31:45 +00:00

QEMU Emulation Targets
======================

To simplify development, the build system supports building images to
work with the QEMU emulator in system emulation mode. Several architectures
are currently supported in 32 and 64 bit variants:

  * ARM (qemuarm + qemuarm64)
  * x86 (qemux86 + qemux86-64)
  * PowerPC (qemuppc only)
  * MIPS (qemumips + qemumips64)

Use of the QEMU images is covered in the Yocto Project Reference Manual.
The appropriate MACHINE variable value corresponding to the target is given
in brackets.
Description
Yocto Project reference distribution Poky
https://yoctoproject.org/
Readme 263 MiB