[uClinux-dev] Re: [PATCH] m68k: merge mmu and non-mmu bitops.h

Greg Ungerer gerg at snapgear.com
Fri Jun 24 01:12:05 EDT 2011


Hi Geert,

On 24/06/11 03:30, Geert Uytterhoeven wrote:
> On Thu, Jun 23, 2011 at 03:28,<gerg at snapgear.com>  wrote:
>> @@ -10,6 +10,9 @@ config ARCH_MAY_HAVE_PC_FDC
>> áconfig ARCH_USES_GETTIMEOFFSET
>> á á á ádef_bool y
>>
>> +config CPU_HAS_BITFIELDS
>> + á á á bool
>> +
>> áconfig EISA
>> á á á ábool
>> á á á á---help---
>> @@ -223,6 +226,7 @@ comment "Processor type"
>>
>> áconfig M68020
>> á á á ábool "68020 support"
>> + á á á select CPU_HAS_BITFIELDS
>> á á á áhelp
>> á á á á áIf you anticipate running this kernel on a computer with a MC68020
>> á á á á áprocessor, say Y. Otherwise, say N. Note that the 68020 requires a
>
> Upon second thought, this won't work for multi-CPU kernels, as there's
> no runtime
> check. The logic needs to be reverted, like:
>
> config CPU_HAS_NO_BITFIELDS
>          bool
>
> config M680000
>          bool "68000 support"
>          select CPU_HAS_NO_BITFIELDS
>
> so a kernel built to run on both 68000 and 68020 will not use the
> bitfield instructions.
> Sorry I didn't realize that earlier.

Yep, good point. I'll rework this again and lets see what that
comes out like.

Regards
Greg


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Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
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