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

[Hallo32 <Hallo32@gmx.net>]

Am 15.08.2017 um 01:39 schrieb Qu Wenruo:
>
>
> 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

Hi,

CFLAGS needs also be replaced by something like HOSTCFLAGS, because if 
you use something like mips/architecture specific CFLAGS, they may be 
not applicably on the host system.

Best regards
>
>>
>>> - 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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>>
>>
>