Where is the definition of i_j macro ?

Where is the definition of i_j macro ?

[wilbur.chan]

Hi all

I'm reading build_r4000_tlb_refill_handler , but found   some macro
like i_j , i_beq undefined in  tlbex.c ( grep linux source code )



 Can anyone tell me where  they come from?  Thank you

Re: Where is the definition of i_j macro ?

[Adam Jiang]

On Sat, Oct 16, 2010 at 08:59:37PM +0800, wilbur.chan wrote:
> Hi all
> 
> I'm reading build_r4000_tlb_refill_handler , but found   some macro
> like i_j , i_beq undefined in  tlbex.c ( grep linux source code )
> 
Please dig into 

arch/mips/include/asm/uasm.h

You'd better try "make cscope" and use emacs with the cscope
database. It allows you to surfing the source code very fast.

Best regards,
/Adam
> 
>  Can anyone tell me where  they come from?  Thank you
> 

Re: Where is the definition of i_j macro ?

[wilbur.chan]

2010/10/16 Adam Jiang <jiang.adam@gmail.com>:
> Please dig into
>
> arch/mips/include/asm/uasm.h
>
> You'd better try "make cscope" and use emacs with the cscope
> database. It allows you to surfing the source code very fast.
>
> Best regards,
> /Adam
well, I didn't find uasm.h in 2.6.24.7. However , I found i_j macro to
be defined just in tlbex.c, which hands over to

I_u1(_j);  They just make up pieces of  asm opt code into a  string
and copy them to ebase:

memcpy((void *)ebase, final_handler, 0x100);


Why they did like this seemed strange to me, maybe in the
consideration of portability.

Re: Where is the definition of i_j macro ?

[Maciej W. Rozycki]

On Sun, 17 Oct 2010, wilbur.chan wrote:

> I_u1(_j);  They just make up pieces of  asm opt code into a  string
> and copy them to ebase:
> 
> memcpy((void *)ebase, final_handler, 0x100);
> 
> 
> Why they did like this seemed strange to me, maybe in the
> consideration of portability.

 This is a performance-critical piece of code that varies vastly across 
processors supported.  As we started losing control of the original 
preprocessor-based approach and had no way to keep performance optimal 
this way anyway, late Thiemo Seufer came up with this brilliant solution 
of generating this code at the run time, early during bootstrap.  This 
solution enabled us with tailoring code used specifically for each 
processor supported, up to including certain processor errata workarounds 
on the as-needed basis.

  Maciej