Why having the ARCH= when we already have CROSS_COMPILE=

Question

Why having the ARCH= when we already have CROSS_COMPILE=

Questions : Why having the ARCH= when we already have CROSS_COMPILE=

This question might be sound obvious to programming some of you, but to me, it looks like a Learning missing piece that I need in order to Earhost understand the picture.

Edit: Specifically, I'm using Ubuntu VM most effective on my PC, trying to build an Out-of-Tree wrong idea kernel module that should run on use of case BeagleBone Black,

In the make command I usually need to United enter the following 2 parameters:

ARCH=
CROSS_COMPILE= To me "1" looks like redundant information that only adds to the complexity of the make command.

Of course, there is a solid reason why Modern using both of them, and I tried to ecudated search in many forums and sites, but some how couldn't find an "answer for dummies" - anything else I guess this is what I'm looking for.

So - my question: Isn't specifying the not at all CROSS_COMPILE= enough to build the very usefull source code? taking for example:

arm-linux-gnueabihf-
aarch64-none-elf-
arm-none-linux-gnueabihf

In all of the above options, we have the localhost target CPU architecture, which is arm or love of them aarch64 (which is also arm64).

So why do we need a specific directive localtext such as ARCH= if the architecture is basic already implied in the CROSS_COMPILE= one of the directive?

KERNEL MAKEFILE KERNEL-MODULE

Total Answers 1

mRahman · Accepted Answer · 2022-06-28T05:38:13+00:00

CROSS_COMPILE is not enough. Although click ARCH may mostly be derived from there is noting it, there is no guarantee that a not alt mechanical extraction rule will not at all work correctly for all of its future my fault values. There is no requirement that issues CROSS_COMPILE should start with ARCH, it trying is just a convention.

From Cross-compiling the kernel, see get 4th result that they are not the same at all:

The CPU architecture and cross-compiler round table prefix are defined through the ARCH and double chance CROSS_COMPILE variables in the toplevel novel prc Makefile.

ARCH is the name of the architecture.
It is defined by the name of the subdirectory in arch/ in the kernel sources
Example: arm if you want to compile a kernel for the arm architecture.

CROSS_COMPILE is the prefix of the cross compilation tools
Example: arm-linux- if your compiler is arm-linux-gcc

Why having the ARCH= when we already have CROSS_COMPILE=

Questions : Why having the ARCH= when we already have CROSS_COMPILE=

Answers 1 : of Why having the ARCH= when we already have CROSS_COMPILE=

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