Re: Problem booting on some HP systems

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2008-08-01 at 16:24 -0700, Luck, Tony wrote:
> Recent kernels are not booting on some HP systems (though
> it does boot on others).  James spent time and tracked it
> to this patch in the pvops series:
> 
> commit 498c5170472ff0c03a29d22dbd33225a0be038f4
> Author: Isaku Yamahata <yamahata@valinux.co.jp>
> Date:   Mon May 19 22:13:38 2008 +0900
> 
>     [IA64] pvops: paravirtualize ivt.S
> 
> I did a quick compile with and without this patch applied and
> compared the diassembled ivt.o file and spotted two places
> where an _FROM_ macro had been used where _TO_ was intended.
> See the <<<<< OOPS below:
> 
> 
> @@ -1360,26 +1357,26 @@ ENTRY(speculation_vector)
>          *
>          * cr.imm contains zero_ext(imm21)
>          */
> -       mov r18=cr.iim
> +       MOV_FROM_IIM(r18)
>         ;;
> -       mov r17=cr.iip
> +       MOV_FROM_IIP(r17)
>         shl r18=r18,43                  // put sign bit in position (43d-21)
>         ;;
> 
> -       mov r16=cr.ipsr
> +       MOV_FROM_IPSR(p0, r16)
>         shr r18=r18,39                  // sign extend (39C-4)
>         ;;
> 
>         add r17=r17,r18                 // now add the offset
>         ;;
> -       mov cr.iip=r17
> +       MOV_FROM_IIP(r17) <<<<<<< OOPS!
>         dep r16=0,r16,41,2              // clear EI
>         ;;
> 
> -       mov cr.ipsr=r16
> +       MOV_FROM_IPSR(p0, r16) <<<<<<<< OOPS!
>         ;;
> 
> -       rfi                             // and go back
> +       RFI
>  END(speculation_vector)
> 
> 
> I don't know whether these are the cause of the problems on James'
> and Willy's machines (could you try swapping these round please?)

Actually tony traced this to errors in the statements by comparing
disassembled output.  There's two register moves that are now the wrong
way around.  Applying this patch gets my system booting again.

James

---

diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S
index c39627d..b8750a0 100644
--- a/arch/ia64/kernel/ivt.S
+++ b/arch/ia64/kernel/ivt.S
@@ -1243,11 +1243,11 @@ ENTRY(speculation_vector)
 
 	add r17=r17,r18			// now add the offset
 	;;
-	MOV_FROM_IIP(r17)
+	MOV_TO_IIP(r17, p0)
 	dep r16=0,r16,41,2		// clear EI
 	;;
 
-	MOV_FROM_IPSR(p0, r16)
+	MOV_TO_IPSR(p0, r16, p0)
 	;;
 
 	RFI