[ECOS] floating point

Jonathan Larmour jifl@eCosCentric.com
Fri Jan 24 08:32:00 GMT 2003


David N. Welton wrote:
> Ok, so I tried a few things to debug it:
> 
> __fpu_switch_vsr:
>         movb $'a',(0xb8000)
> 
> And I don't see it showing up.
> 
> The code to intall __fpu_switch_vsr is getting run, but it
> doesn't seem to set things up quite right.
> 
> This makes things work ok:
> 
> 	hal_pc_exception_noerr  4
> 	hal_pc_exception_noerr  5	
> 	hal_pc_exception_noerr  6
> #	hal_pc_exception_noerr  7
> hal_pc_exception_7:
> 	movl	$0,hal_trap_error_code
> 	pushl	$7
> 	incl	(hal_vsr_stats+7*4)
> 	jmp	__fpu_switch_vsr
> 
> Trying to figure out why it's not setting things up automatically.

But that code only applies for lazy FPU switching. In arch.inc it's 
clearly in that ifdef. And if you want to debug an FPU problem here, 
definitely keep the lazy switching off.

Jifl
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