Re: btrfs-progs-v4.12: cross compiling

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2017年08月15日 02:57, Goffredo Baroncelli wrote:
> On 08/14/2017 05:10 PM, David Sterba wrote:
>> On Mon, Aug 14, 2017 at 10:14:42PM +0800, Qu Wenruo wrote:
> [...]
>> mktables.c is synced from kernel sources, taking updates from there is
>> easier than porting any changes to the proposed scripted implementation.
>>
>> The workflow is simple:
>> - copy kernel mktables.c changes to btrfs-progs mktables.c
> 
> How the kernel deals with this kind of problem ?
> Looking at the source of btrfs Makefile, it is more simple to replace
> 
>    mktables: kernel-lib/mktables.c
>          @echo "    [CC]     $@"
>          $(Q)$(CC) $(CFLAGS) $< -o $@
> 
> with
> 
> 
>    mktables: kernel-lib/mktables.c
>          @echo "    [HOSTCC] $@"
>          $(Q)$(HOSTCC) $(CFLAGS) $< -o $@
> 
> where HOSTCC is defined as
> 
> HOSTCC=gcc
> 
> 
> (may be the same applied also to CFLAGS <-> HOSTCFLAGS ?)

If using HOSTCC then I'm fine with it.

Thanks,
Qu

> 
>> - compile mktables
>> - run 'make kernel-lib/tables.c'
>> - commit the changes to git
>>
>> All of that happens very rarely, if ever, the raid56 tables and
>> correction algorithms are set in stone. Any extensions need to be done
>> on both sides kernel/userspace.
>>
>>>>> What about using script to generate it?
>>>>
>>>> We do have the mktables utility to generate it and I'll regenerate it
>>>> should there be a change to kernel-lib/mktables.c
>>>
>>> I mean to replace mktables.c with a script.
>>> So no cross compiler problems at all, and even easier Makefile.
>>> No dependence on "mktables" program.
>>
>> Somebody has to implement the script and verify that the output is the
>> same, eventually sync changes. The cross-compilation should be fixed
>> with the pregenerated tables.c . Is Makefile size really a concern? The
>> number of related lines is like 7. I don't see any benefit in what you
>> propose and hopefully explained my viewpoint enough so I don't have to
>> continue.
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> 
>