Set INSTALL_HDR_PATH on command line

Set INSTALL_HDR_PATH on command line

[Jonas Bonn]

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In the toplevel Linux Makefile, INSTALL_HDR_PATH is hardcoded as
follows:

# Kernel headers

#Default location for installed headers
export INSTALL_HDR_PATH = $(objtree)/usr

Should this not be done with ?= so that the install path can be
overridden on the command line?

export INSTALL_HDR_PATH ?= $(objtree)/usr

This would make installation of headers for cross-build environments
simpler.  Or am I missing something else?

Regards,
Jonas

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Re: Set INSTALL_HDR_PATH on command line

[Sam Ravnborg]

On Thu, Apr 22, 2010 at 09:23:28AM +0200, Jonas Bonn wrote:
> In the toplevel Linux Makefile, INSTALL_HDR_PATH is hardcoded as
> follows:
> 
> # Kernel headers
> 
> #Default location for installed headers
> export INSTALL_HDR_PATH = $(objtree)/usr
> 
> Should this not be done with ?= so that the install path can be
> overridden on the command line?
> 
> export INSTALL_HDR_PATH ?= $(objtree)/usr

What you can do today is:

    make INSTALL_HDR_PATH=/my/dir


Difference between "=" and "?=" is that the latter
only assign a new value if the variables was not defined.

	Sam