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Re: Which ARM architectures need support? (was Re: Restructuring trapframe)

On 20 Sep, 2013, at 22:17 , Matt Thomas <matt%3am-software.com@localhost> wrote:
>> I think I get now that all assembly code needs to be runnable on
>> armv4.  Am I right that the architecture defines used in <arm/cdefs.h>
>> can be relied upon to tell you what the compiler is compiling for, so
>> that if what is required to make it run on armv4 seems offensively
>> expensive a nicer alternative when compiling for more modern CPUs
>> can be #ifdef'd in?  
> Yes.
>> Also, if __builtin_clz() and __builtin_clzll() are
>> used in a kernel compiled for a CPU missing the instructions, are the
>> run-time functions it instead emits calls to available?
> Yes they are.

Perfect, thanks.

Dennis Ferguson

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