[OE-core] What is TOOLCHAIN_NEED_CONFIGSITE_CACHE for?

[Chris Larson]

On Mon, Oct 29, 2012 at 8:43 AM, Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
> On Mon, 2012-10-29 at 13:33 +0000, Phil Blundell wrote:
>> This morning I happened to notice that some/all of my images had a
>> dependency on ncurses for no obviously good reason.  (Following an
>> earlier small crusade these are now the only remaining dependencies on
>> ncurses in my build, so I would quite like to get rid of them.)
>>
>> It turns out that the dependency in question is due to the code in
>> toolchain-scripts.bbclass (which is inherited from
>> populate_sdk_base.bbclass, from image.bbclass) which does:
>>
>> TOOLCHAIN_NEED_CONFIGSITE_CACHE = "${TCLIBC} ncurses"
>>
>> [...]
>>
>> python __anonymous () {
>>     deps = ""
>>     for dep in (d.getVar('TOOLCHAIN_NEED_CONFIGSITE_CACHE', True) or "").split():
>>         deps += " %s:do_populate_sysroot" % dep
>>     d.appendVarFlag('do_configure', 'depends', deps)
>> }
>>
>> The code in question was added in:
>>
>> commit 9e87f1347788beed181476dc4563085db14a4729
>> Author: Lianhao Lu <lianhao.lu at intel.com>
>> Date:   Tue Aug 16 11:15:36 2011 +0800
>>
>>     toolchain-script.bbclass: Collected cached site config in runtime.
>>
>>     [YOCTO #892]
>>     Modify the function toolchain_create_sdk_siteconfig to collect the
>>     cached site config files which are specified by
>>     TOOLCHAIN_NEED_CONFIGSITE_CACHE in runtime.
>>
>>     Also added task dependency to ensure the cached site config files are
>>     generated.
>>
>>     Signed-off-by: Lianhao Lu <lianhao.lu at intel.com>
>>
>> ... but I don't entirely understand from that commentary what exactly is
>> special about ncurses that means it needs to be handled this way.  Can
>> anybody clarify?
>
> We ship the "site" cache files with the toolchain. We decided to include
> the generated cache files as well as the static ones. We currently
> generate "site" files for libc and ncurses.
>
> You can almost certainly just set:
>
> TOOLCHAIN_NEED_CONFIGSITE_CACHE = "${TCLIBC}"
>
> and be happy since this just lists which generated cache site files to
> include.

Shouldn't it be pulled in via depends from the populate_sdk bits,
rather than a task that's used both for image builds and toolchain
builds, though?
-- 
Christopher Larson