Re: [Qemu-devel] [PATCH] SH4: Fixed last UTLB unused

[Lionel Landwerlin <lionel.landwerlin@openwide.fr>]

Le mardi 03 mars 2009 à 07:15 +0100, Aurelien Jarno a écrit :
> On Sun, Feb 22, 2009 at 01:05:37AM +0100, Lionel Landwerlin wrote:
> > Still not happy with the fix ...
> > 
> > Signed-off-by: Lionel Landwerlin <lionel.landwerlin@openwide.fr>
> > ---
> >  target-sh4/helper.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> Sorry I missed this one when committing the first patch. I have applied
> it on top of it.
> 
> > diff --git a/target-sh4/helper.c b/target-sh4/helper.c
> > index cd0f392..8498d3f 100644
> > --- a/target-sh4/helper.c
> > +++ b/target-sh4/helper.c
> > @@ -305,7 +305,7 @@ static void increment_urc(CPUState * env)
> >      urb = ((env->mmucr) >> 18) & 0x3f;
> >      urc = ((env->mmucr) >> 10) & 0x3f;
> >      urc++;
> > -    if (urc == urb || urc == UTLB_SIZE - 1)
> > +    if (urc > urb || urc > (UTLB_SIZE - 1))
> >  	urc = 0;
> >      env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
> >  }
> > -- 
> > 1.5.6.5

Hi Aurelien,

Thanks for applying my patches, but even with this version, I was still
missing the real condition (according to SH4 datasheet) :

        Random counter for indicating the UTLB entry for which
        replacement is to be performed with an LDTLB instruction. URC
        is incremented each time the UTLB is accessed. When URB > 0,
        URC is reset to 0 when the condition URC = URB occurs. Also
        note that, if a value is written to URC by software which
        results in
        the condition URC > URB, incrementing is first performed in
        excess of URB until URC = 0x3F. URC is not incremented by an
        LDTLB instruction.
        
So the final version is :


[PATCH] SH4: Fixed last UTLB unused and URB/URC management

Signed-off-by: Lionel Landwerlin <lionel.landwerlin@openwide.fr>
---
 target-sh4/helper.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/target-sh4/helper.c b/target-sh4/helper.c
index cd0f392..54a3f1f 100644
--- a/target-sh4/helper.c
+++ b/target-sh4/helper.c
@@ -297,7 +297,7 @@ static int same_tlb_entry_exists(const tlb_t *
haystack, uint8_t nbtlb,
     return 0;
 }
 
static void increment_urc(CPUState * env)
 {
     uint8_t urb, urc;
 
@@ -305,7 +305,7 @@ static void increment_urc(CPUState * env)
     urb = ((env->mmucr) >> 18) & 0x3f;
     urc = ((env->mmucr) >> 10) & 0x3f;
     urc++;
-    if (urc == urb || urc == UTLB_SIZE - 1)
+    if ((urb > 0 && urc > urb) || urc > (UTLB_SIZE - 1))
 	urc = 0;
     env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
 }
-- 
1.5.6.5



Sorry for that mistake.


-- 
Lionel Landwerlin <lionel.landwerlin@openwide.fr>