[OE-core] [Yocto] The design document for ccache-native

[Tom Rini]

On 06/09/2011 07:54 PM, Khem Raj wrote:
> On 06/09/2011 04:51 PM, Tom Rini wrote:
>> On 06/09/2011 03:40 PM, Saul Wold wrote:
>>> On 06/02/2011 08:11 PM, wenzong fan wrote:
>>>> Hi Folks,
>>>>
>>>> Please help me to review the design document for ccache-native, and
>>>> I also have two questions about it, any answers or suggestions are
>>>> appreciated.
>>>>
>>>> * Feature name: ccache-native
>>>>      Priority: P3; M2
>>>>      Owner: Wenzong Fan
>>>>      Summary: Integrate ccache-native to yocto
>>>>
>>>> * Description:
>>>> Bitbake supports the 'CCACHE Mechanism', but 'ccache' hasn't been
>>>> included by poky/yocto, just add it as a native tool.
>>>>
>>>> * Usage:
>>>> Build ccache as a native tool by default and enable it for speeding
>>>> target packages build.
>>>>
>>>> * Implementation:
>>>> 1) Copy bb file from OE upstream to:
>>>>        meta/recipes-devtools/ccache/
>>>>
>>>> 2) Update bb file to get the latest ccache_3.1.5 and split the single
>>>> bb file to:
>>>>        'ccache_3.1.5.bb', 'ccache.inc'
>>>>
>>>> 3) Enable ccache in the native tools building.
>>>>
>>> You will need to have it be a dependency pretty early on in the build.
>>> Additionally, this is a bit a new part to this task, we want to have the
>>> default CCACHE_DIR for the build default to a directory in TMPDIR
>>> instead of the user's home directory.  This will mean setting an
>>> environment variable somewhere early also.
>>
>> Can we instead veto ccache and remove it from the bitbake docs?  I can't
>> count the number of times I've run into what I can only imagine are
>> ccache conflicts to explain why a random build failure with ccache in
>> use.
> 
> It works on some hosts somewhat reliably and is unpredictable on some as
> you say. I think keeping it optional is probably the right thing but
> making it default may not be a good thing.

I'm pretty sure it's not reliable so much as lucky, but shoving the
cache somewhere else and making it per-recipe makes me less worried.

-- 
Tom Rini
Mentor Graphics Corporation