Hi Marko
Thanks, that has deepened my understanding, and confirms what I had
guessed / inferred. I will update my blog later with a simplified
version of your explanation.
Chris
Zitat von "Marko Koschak" <marko.kosc...@tisno.de>:
Hi Matze
On So, 2013-12-22 at 21:50 +0100, christopher.l...@thurweb.ch wrote:
The SDK Build Engine is a little bit more tricky.
Once you SSH in, zypper is available, but if you zypper at that level,
all you are doing is adding stuff to the operating system.
Within this VM is SB2, which is the Build Engine itself. Others on
this mailist are much better qualified than me to tell you more about
it.
If you are familiar with the term chroot (change-root) then you could
thing of SB2 (Scratchbox2) just as an chroot environment running armv7hl
emulated code (through qemu) where you actually build your source rpm
package. SB2 comes from the "legacy" of cross-compiling. The problem
with cross-compiling is that you need to tell your compiler not to use
the host (x86) tools and libs for compiling but the equivalent tools and
libs from the target (armv7hl) system. There are multiple approaches to
overcome that. One is to tell the compiler (via e.g. configure,
makefile,...) where to find that stuff or you don't tell the compiler
that (less work to create a makefile that cross-compiles too) but alter
your environment that the compiler "thinks" it is running on the target
(armv7hl) system itself. This is what SB2 actually does. That is very
useful if you want to compile just any "normal" rpm package (from the
linux userland stack) without adapting it to the target architecture.
(In detail SB2 is not a "full" chroot system, but it uses fakeroot which
enables SB2 to use host tools for speed up compilation instead of
running arm binaries in slow emulation mode. It's quite some time ago I
used SB2 but I hope I got it right and you got a rough idea... :)
Cheers,
Marko
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