[patch 0/5] SiByte fixes for 2.6.12

[patch 0/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

The following series of patches address a few issues I ran into while
getting 2.6.12 running on Swarm.  Some of them are questionable, for
example [3/5] is only an issue because of the oldish toolchain I happen
to be using at the moment.

Also, Ralf, do you like these quilt-style patchbombs or do you prefer
another submission format?

-andy

[patch 1/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

SB1 does not use the R4K TLB code.

Signed-Off-By: Andrew Isaacson <adi@broadcom.com>

Index: linux-2.6-work/arch/mips/kernel/cpu-probe.c
===================================================================
--- linux-2.6-work.orig/arch/mips/kernel/cpu-probe.c	2005-06-22 11:17:22.000000000 -0700
+++ linux-2.6-work/arch/mips/kernel/cpu-probe.c	2005-06-22 11:17:29.000000000 -0700
@@ -583,6 +583,8 @@
 	switch (c->processor_id & 0xff00) {
 	case PRID_IMP_SB1:
 		c->cputype = CPU_SB1;
+		c->options &= ~MIPS_CPU_4KTLB;
+		c->options |= MIPS_CPU_TLB;
 #ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
 		/* FPU in pass1 is known to have issues. */
 		c->options &= ~(MIPS_CPU_FPU | MIPS_CPU_32FPR);

--

[patch 2/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

Update sb1250_set_affinity to use cpumask_t rather than hand-rolled
bitmask code.

Signed-Off-By: Andrew Isaacson <adi@broadcom.com>

Index: linux-2.6-work/arch/mips/sibyte/sb1250/irq.c
===================================================================
--- linux-2.6-work.orig/arch/mips/sibyte/sb1250/irq.c	2005-06-22 11:17:21.000000000 -0700
+++ linux-2.6-work/arch/mips/sibyte/sb1250/irq.c	2005-06-22 11:17:30.000000000 -0700
@@ -53,7 +53,7 @@
 static unsigned int startup_sb1250_irq(unsigned int irq);
 static void ack_sb1250_irq(unsigned int irq);
 #ifdef CONFIG_SMP
-static void sb1250_set_affinity(unsigned int irq, unsigned long mask);
+static void sb1250_set_affinity(unsigned int irq, cpumask_t mask);
 #endif
 
 #ifdef CONFIG_SIBYTE_HAS_LDT
@@ -117,23 +117,16 @@
 }
 
 #ifdef CONFIG_SMP
-static void sb1250_set_affinity(unsigned int irq, unsigned long mask)
+static void sb1250_set_affinity(unsigned int irq, cpumask_t mask)
 {
 	int i = 0, old_cpu, cpu, int_on;
 	u64 cur_ints;
 	irq_desc_t *desc = irq_desc + irq;
 	unsigned long flags;
 
-	while (mask) {
-		if (mask & 1) {
-			mask >>= 1;
-			break;
-		}
-		mask >>= 1;
-		i++;
-	}
+	i = first_cpu(mask);
 
-	if (mask) {
+	if (cpus_weight(mask) > 1) {
 		printk("attempted to set irq affinity for irq %d to multiple CPUs\n", irq);
 		return;
 	}

--

[patch 3/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

Toolchain compat fix: gas 2.12.1 doesn't understand two-argument jalr,
and the $ra is redundant anyways.

Signed-Off-By: Andrew Isaacson <adi@broadcom.com>

Index: linux-2.6-work/arch/mips/lib/uncached.c
===================================================================
--- linux-2.6-work.orig/arch/mips/lib/uncached.c	2005-06-22 11:17:21.000000000 -0700
+++ linux-2.6-work/arch/mips/lib/uncached.c	2005-06-22 11:17:31.000000000 -0700
@@ -26,7 +26,7 @@
 	__asm__ __volatile__ (
 		"	move $16, $sp\n"
 		"	move $sp, %1\n"
-		"	jalr $ra, %2\n"
+		"	jalr %2\n"
 		"	move $sp, $16"
 		: "=&r" (ret)
 		: "r" (usp), "r" (ufunc)

--

[patch 4/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

If the CPU Options get out of sync with the CONFIG_CPU_ options,
cpu_cache_init() can end up being a noop.  Stop with a useful message
in that case rather than running on without cache functions.

Signed-Off-By: Andrew Isaacson <adi@broadcom.com>

Index: linux-2.6-work/arch/mips/mm/cache.c
===================================================================
--- linux-2.6-work.orig/arch/mips/mm/cache.c	2005-06-22 11:17:20.000000000 -0700
+++ linux-2.6-work/arch/mips/mm/cache.c	2005-06-22 11:17:32.000000000 -0700
@@ -122,6 +122,8 @@
     defined(CONFIG_CPU_MIPS64) || defined(CONFIG_CPU_TX49XX) || \
     defined(CONFIG_CPU_RM7000) || defined(CONFIG_CPU_RM9000)
 		ld_mmu_r4xx0();
+#else
+    		panic("Unknown CPU with r4k TLB");
 #endif
 	} else switch (current_cpu_data.cputype) {
 #ifdef CONFIG_CPU_R3000

--

[patch 5/5] SiByte fixes for 2.6.12

[Andrew Isaacson]

Fix a stale comment in c-sb1.c.

Signed-Off-By: Andrew Isaacson <adi@broadcom.com>

Index: linux-2.6-work/arch/mips/mm/c-sb1.c
===================================================================
--- linux-2.6-work.orig/arch/mips/mm/c-sb1.c	2005-06-22 11:17:18.000000000 -0700
+++ linux-2.6-work/arch/mips/mm/c-sb1.c	2005-06-22 11:17:33.000000000 -0700
@@ -492,7 +492,7 @@
 }
 
 /*
- * This is called from loadmmu.c.  We have to set up all the
+ * This is called from cache.c.  We have to set up all the
  * memory management function pointers, as well as initialize
  * the caches and tlbs
  */

--

Re: [patch 1/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Wed, 22 Jun 2005, Andrew Isaacson wrote:

> SB1 does not use the R4K TLB code.

 Well, the flag is not really to specify whether the common code is to be 
used or not.  It's about whether the TLB is like that of the R4k.  
Actually it's always been a mystery for me why the common code cannot be 
used for the SB1, but perhaps there is something specific that I could 
only discover in that "SB-1 Core User Manual" that I yet have to see, 
sigh...

 Of course if your TLB is indeed different from that of the R4k, then you 
shouldn't be setting cp0.config.mt to 1 in the first place...

  Maciej

Re: [patch 3/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Wed, 22 Jun 2005, Andrew Isaacson wrote:

> Toolchain compat fix: gas 2.12.1 doesn't understand two-argument jalr,
> and the $ra is redundant anyways.

 Is it really the case?  Perhaps it doesn't know the symbolic name of the 
register which has only been added recently.  Replacing it with $31 should 
fix the problem, but your patch is obviously correct regardless.

 The code is broken anyway -- I've tried fixing it, but I've hit 
shortcomings of macros in <asm/addrspace.h> (I've got working code, but 
GCC complains loudly), so it may yet take a while.

  Maciej

Re: [patch 4/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Wed, 22 Jun 2005, Andrew Isaacson wrote:

> If the CPU Options get out of sync with the CONFIG_CPU_ options,
> cpu_cache_init() can end up being a noop.  Stop with a useful message
> in that case rather than running on without cache functions.

 Wouldn't a build-time error be a better option?

  Maciej

Re: [patch 4/5] SiByte fixes for 2.6.12

[Andy Isaacson]

On Thu, Jun 23, 2005 at 12:08:39PM +0100, Maciej W. Rozycki wrote:
> On Wed, 22 Jun 2005, Andrew Isaacson wrote:
> > If the CPU Options get out of sync with the CONFIG_CPU_ options,
> > cpu_cache_init() can end up being a noop.  Stop with a useful message
> > in that case rather than running on without cache functions.
> 
>  Wouldn't a build-time error be a better option?

The code looks like it's structured to be able to be compiled with
support for multiple CPUs, say, r4k and SB1; using #error would seem to
prevent that.

With the code as currently structured, you don't know it's going to be a
noop until runtime comes along and cpu_has_4ktlb is true...

-andy

Re: [patch 4/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Thu, 23 Jun 2005, Andy Isaacson wrote:

> The code looks like it's structured to be able to be compiled with
> support for multiple CPUs, say, r4k and SB1; using #error would seem to
> prevent that.
> 
> With the code as currently structured, you don't know it's going to be a
> noop until runtime comes along and cpu_has_4ktlb is true...

 Well, I've had a look at the code and it's such a mess.  Obviously 
calling ld_mmu_r4xx0() (or any of the other variants) should not be 
compiled conditionally and more specific cases, i.e. based on PRId values 
should take precedence.  I'll see if I can make it better.

  Maciej

Re: [patch 3/5] SiByte fixes for 2.6.12

[Andy Isaacson]

On Thu, Jun 23, 2005 at 12:07:48PM +0100, Maciej W. Rozycki wrote:
> On Wed, 22 Jun 2005, Andrew Isaacson wrote:
> > Toolchain compat fix: gas 2.12.1 doesn't understand two-argument jalr,
> > and the $ra is redundant anyways.
> 
>  Is it really the case?  Perhaps it doesn't know the symbolic name of the 
> register which has only been added recently.  Replacing it with $31 should 
> fix the problem, but your patch is obviously correct regardless.

Yeah, you're right, my old gas just doesn't know $ra.  s/ra/31/g works
as well.

-andy

Re: [patch 4/5] SiByte fixes for 2.6.12

[Andy Isaacson]

On Thu, Jun 23, 2005 at 04:11:51PM +0100, Maciej W. Rozycki wrote:
> On Thu, 23 Jun 2005, Andy Isaacson wrote:
> > The code looks like it's structured to be able to be compiled with
> > support for multiple CPUs, say, r4k and SB1; using #error would seem to
> > prevent that.
> > 
> > With the code as currently structured, you don't know it's going to be a
> > noop until runtime comes along and cpu_has_4ktlb is true...
> 
>  Well, I've had a look at the code and it's such a mess.  Obviously 
> calling ld_mmu_r4xx0() (or any of the other variants) should not be 
> compiled conditionally and more specific cases, i.e. based on PRId values 
> should take precedence.  I'll see if I can make it better.

I certainly won't argue with a cleanup of arch/mips/mm/cache.c, that
code has annoyed me from first laying eyes on it...

-andy

Re: [patch 1/5] SiByte fixes for 2.6.12

[Andy Isaacson]

On Thu, Jun 23, 2005 at 12:01:57PM +0100, Maciej W. Rozycki wrote:
> On Wed, 22 Jun 2005, Andrew Isaacson wrote:
> > SB1 does not use the R4K TLB code.
> 
>  Well, the flag is not really to specify whether the common code is to be 
> used or not.  It's about whether the TLB is like that of the R4k.  
> Actually it's always been a mystery for me why the common code cannot be 
> used for the SB1, but perhaps there is something specific that I could 
> only discover in that "SB-1 Core User Manual" that I yet have to see, 
> sigh...
> 
>  Of course if your TLB is indeed different from that of the R4k, then you 
> shouldn't be setting cp0.config.mt to 1 in the first place...

So I don't know everything that went on during the SB1 MIPS port, but
what I see at this point makes at least some sense to me.  The SB1 has
some fancy features that are used in c-sb1.c and thereabouts (the DMA
pageops, and avoiding work by using the coherency guarantees, among
others).

While it is worthwhile to abstract that code out some more (and I
consider it a long-term goal to share as much code as possible with the
generic r4k/mips32/mips64 code), it works as is and it's not obvious
what small simplifications should be taken at this point.  (Or at least,
I'm not smart enough to see what obvious small simplifications should be
done.)  So for the time being I'm in favor of doing what's needed to
keep the support from bit-rotting.  I'll keep an eye on whatever
cleanups you end up doing and keep them up to date with our internal
tree...

That said, I'm open to suggestions as to what I should do in the short
term to get the right results.

-andy

Re: [patch 3/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Thu, 23 Jun 2005, Andy Isaacson wrote:

> >  Is it really the case?  Perhaps it doesn't know the symbolic name of the 
> > register which has only been added recently.  Replacing it with $31 should 
> > fix the problem, but your patch is obviously correct regardless.
> 
> Yeah, you're right, my old gas just doesn't know $ra.  s/ra/31/g works
> as well.

 Here's my proposal to fix run_uncached() -- it works correctly for me for 
both 32-bit and 64-bit builds (current code crashes for me for 64 bits, 
because as a result of the bad calculation a jump outside any valid 
address space is attempted).  I've inspected generated machine code to 
make sure it's correct as well.

 Unfortunately with this code GCC spits out a few bogus warnings for 
32-bit builds (this is supposed to be a "non-bug" of the compiler -- see 
"http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12963" for details).  I'm not 
sure struggling hard to get rid of these warnings, possibly complicating 
code, is worth the hassle; GCC should be fixed instead.

 Unless there are objections I'd like to apply this patch.

  Maciej

patch-mips-2.6.12-20050620-run_uncached-8
diff -up --recursive --new-file linux-mips-2.6.12-20050620.macro/arch/mips/lib/uncached.c linux-mips-2.6.12-20050620/arch/mips/lib/uncached.c
--- linux-mips-2.6.12-20050620.macro/arch/mips/lib/uncached.c	2005-04-25 16:36:23.000000000 +0000
+++ linux-mips-2.6.12-20050620/arch/mips/lib/uncached.c	2005-06-23 18:24:58.000000000 +0000
@@ -4,31 +4,71 @@
  * for more details.
  *
  * Copyright (C) 2005 Thiemo Seufer
+ * Copyright (C) 2005  MIPS Technologies, Inc.  All rights reserved.
+ *	Author: Maciej W. Rozycki <macro@mips.com>
  */
+
 #include <linux/init.h>
 
 #include <asm/addrspace.h>
+#include <asm/bug.h>
+
+#ifndef CKSEG2
+#define CKSEG2 CKSSEG
+#endif
+#ifndef TO_PHYS_MASK
+#define TO_PHYS_MASK -1
+#endif
 
 /*
- * FUNC is executed in the uncached segment CKSEG1. This works only if
- * both code and stack live in CKSEG0. The stack handling works because
- * we don't handle stack arguments or more complex return values, so we
- * can avoid to share the same stack area between cached and uncached
- * mode.
+ * FUNC is executed in one of the uncached segments, depending on its
+ * original address as follows:
+ *
+ * 1. If the original address is in CKSEG0 or CKSEG1, then the uncached
+ *    segment used is CKSEG1.
+ * 2. If the original address is in XKPHYS, then the uncached segment
+ *    used is XKPHYS(2).
+ * 3. Otherwise it's a bug.
+ *
+ * The same remapping is done with the stack pointer.  Stack handling
+ * works because we don't handle stack arguments or more complex return
+ * values, so we can avoid sharing the same stack area between a cached
+ * and the uncached mode.
  */
 unsigned long __init run_uncached(void *func)
 {
-	register unsigned long sp __asm__("$sp");
-	register unsigned long ret __asm__("$2");
-	unsigned long usp = sp - CAC_BASE + UNCAC_BASE;
-	unsigned long ufunc = func - CAC_BASE + UNCAC_BASE;
+	register long sp __asm__("$sp");
+	register long ret __asm__("$2");
+	long lfunc = (long)func, ufunc;
+	long usp;
+
+	if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
+		usp = CKSEG1ADDR(sp);
+	else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0LL, 0) &&
+		 (long long)sp < (long long)PHYS_TO_XKPHYS(8LL, 0))
+		usp = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED,
+				     XKPHYS_TO_PHYS((long long)sp));
+	else {
+		BUG();
+		usp = sp;
+	}
+	if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2)
+		ufunc = CKSEG1ADDR(lfunc);
+	else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0LL, 0) &&
+		 (long long)lfunc < (long long)PHYS_TO_XKPHYS(8LL, 0))
+		ufunc = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED,
+				       XKPHYS_TO_PHYS((long long)lfunc));
+	else {
+		BUG();
+		ufunc = lfunc;
+	}
 
 	__asm__ __volatile__ (
-		"	move $16, $sp\n"
-		"	move $sp, %1\n"
-		"	jalr $ra, %2\n"
-		"	move $sp, $16"
-		: "=&r" (ret)
+		"	move	$16, $sp\n"
+		"	move	$sp, %1\n"
+		"	jalr	%2\n"
+		"	move	$sp, $16"
+		: "=r" (ret)
 		: "r" (usp), "r" (ufunc)
 		: "$16", "$31");
 

Re: [patch 3/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Thu, 30 Jun 2005, Maciej W. Rozycki wrote:

>  Unless there are objections I'd like to apply this patch.

 Thus it's now in.

  Maciej

Re: [patch 1/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Thu, Jun 23, 2005 at 12:01:57PM +0100, Maciej W. Rozycki wrote:

>  Well, the flag is not really to specify whether the common code is to be 
> used or not.  It's about whether the TLB is like that of the R4k.  
> Actually it's always been a mystery for me why the common code cannot be 
> used for the SB1, but perhaps there is something specific that I could 
> only discover in that "SB-1 Core User Manual" that I yet have to see, 
> sigh...
> 
>  Of course if your TLB is indeed different from that of the R4k, then you 
> shouldn't be setting cp0.config.mt to 1 in the first place...

The reason was primarily the tiny bit of extra performance because the
SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few
changes that are needed to initialize a TLB in undefined state after
powerup.  That was needed to run Linux on firmware-less SB1 cores.

  Ralf

Re: [patch 1/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Wed, Jun 22, 2005 at 04:00:42PM -0700, Andrew Isaacson wrote:

> SB1 does not use the R4K TLB code.

Now it does :-)

  Ralf

Re: [patch 4/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Thu, Jun 23, 2005 at 03:27:09PM -0700, Andy Isaacson wrote:

> >  Well, I've had a look at the code and it's such a mess.  Obviously 
> > calling ld_mmu_r4xx0() (or any of the other variants) should not be 
> > compiled conditionally and more specific cases, i.e. based on PRId values 
> > should take precedence.  I'll see if I can make it better.
> 
> I certainly won't argue with a cleanup of arch/mips/mm/cache.c, that
> code has annoyed me from first laying eyes on it...

So just did that, cpu_cache_init is looking bearable now.

  Ralf

Re: [patch 5/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Wed, Jun 22, 2005 at 04:02:03PM -0700, Andrew Isaacson wrote:

> Fix a stale comment in c-sb1.c.

Applied,

  Ralf

Re: [patch 1/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Sat, 1 Oct 2005, Ralf Baechle wrote:

> >  Of course if your TLB is indeed different from that of the R4k, then you 
> > shouldn't be setting cp0.config.mt to 1 in the first place...
> 
> The reason was primarily the tiny bit of extra performance because the
> SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few

 That's hardly a justification for duplicating all the code; I've thought 
the reason was actually historical -- hadn't it been simply written 
separately initially and never got merged properly afterwards?

> changes that are needed to initialize a TLB in undefined state after
> powerup.  That was needed to run Linux on firmware-less SB1 cores.

 But that's true about the power-up state of the TLB on any MIPS CPU, 
isn't it?

  Maciej

Re: [patch 1/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Mon, Oct 03, 2005 at 12:56:20PM +0100, Maciej W. Rozycki wrote:

> > >  Of course if your TLB is indeed different from that of the R4k, then you 
> > > shouldn't be setting cp0.config.mt to 1 in the first place...
> > 
> > The reason was primarily the tiny bit of extra performance because the
> > SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few
> 
>  That's hardly a justification for duplicating all the code; I've thought 
> the reason was actually historical -- hadn't it been simply written 
> separately initially and never got merged properly afterwards?

Historically even the R10000 had it's own copy of the TLB code - with
the sole reason of existence being it having neither hazards nor suffering
from potencial duplicate TLB entries.  Well, maybe also the very first
stages of MIPS SMP support.

Anyway, as you said that's little reason for an extra copy to exist and
so I both got axed.

> > changes that are needed to initialize a TLB in undefined state after
> > powerup.  That was needed to run Linux on firmware-less SB1 cores.
> 
>  But that's true about the power-up state of the TLB on any MIPS CPU, 
> isn't it?

Some come out of powerup with a cleared TLB but anyway, since normally
some piece of firmware takes care of these issues it's not something
Linux normally should need to worry about.

  Ralf

Re: [patch 1/5] SiByte fixes for 2.6.12

[Daniel Jacobowitz]

On Sat, Oct 01, 2005 at 10:28:07AM +0100, Ralf Baechle wrote:
> On Thu, Jun 23, 2005 at 12:01:57PM +0100, Maciej W. Rozycki wrote:
> 
> >  Well, the flag is not really to specify whether the common code is to be 
> > used or not.  It's about whether the TLB is like that of the R4k.  
> > Actually it's always been a mystery for me why the common code cannot be 
> > used for the SB1, but perhaps there is something specific that I could 
> > only discover in that "SB-1 Core User Manual" that I yet have to see, 
> > sigh...
> > 
> >  Of course if your TLB is indeed different from that of the R4k, then you 
> > shouldn't be setting cp0.config.mt to 1 in the first place...
> 
> The reason was primarily the tiny bit of extra performance because the
> SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few
> changes that are needed to initialize a TLB in undefined state after
> powerup.  That was needed to run Linux on firmware-less SB1 cores.

FYI, all I have is a piece of hard evidence: this patch was the
difference between not booting and booting for a Sentosa with CFE. 
Which isn't firmwareless and isn't a tiny bit of extra performance
issue.

I'll try to give CVS HEAD a shot this week sometime.

-- 
Daniel Jacobowitz
CodeSourcery, LLC

Re: [patch 1/5] SiByte fixes for 2.6.12

[Ralf Baechle]

On Mon, Oct 03, 2005 at 09:15:52AM -0400, Daniel Jacobowitz wrote:

> > >  Well, the flag is not really to specify whether the common code is to be 
> > > used or not.  It's about whether the TLB is like that of the R4k.  
> > > Actually it's always been a mystery for me why the common code cannot be 
> > > used for the SB1, but perhaps there is something specific that I could 
> > > only discover in that "SB-1 Core User Manual" that I yet have to see, 
> > > sigh...
> > > 
> > >  Of course if your TLB is indeed different from that of the R4k, then you 
> > > shouldn't be setting cp0.config.mt to 1 in the first place...
> > 
> > The reason was primarily the tiny bit of extra performance because the
> > SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few
> > changes that are needed to initialize a TLB in undefined state after
> > powerup.  That was needed to run Linux on firmware-less SB1 cores.
> 
> FYI, all I have is a piece of hard evidence: this patch was the
> difference between not booting and booting for a Sentosa with CFE. 
> Which isn't firmwareless and isn't a tiny bit of extra performance
> issue.
> 
> I'll try to give CVS HEAD a shot this week sometime.

Just as reminder for everybody - CVS is dead and frozen, the action is
playing on git now ...

  Ralf

Re: [patch 1/5] SiByte fixes for 2.6.12

[Maciej W. Rozycki]

On Mon, 3 Oct 2005, Daniel Jacobowitz wrote:

> FYI, all I have is a piece of hard evidence: this patch was the
> difference between not booting and booting for a Sentosa with CFE. 
> Which isn't firmwareless and isn't a tiny bit of extra performance
> issue.

 Actually workarounds have been floating around for some time. ;-)  But 
I'm glad this has now been fixed properly.

  Maciej

Re: [patch 1/5] SiByte fixes for 2.6.12

[Martin Michlmayr]

* Andrew Isaacson <adi@broadcom.com> [2005-06-22 16:00]:
> SB1 does not use the R4K TLB code.
> 
>  		c->cputype = CPU_SB1;
> +		c->options &= ~MIPS_CPU_4KTLB;
> +		c->options |= MIPS_CPU_TLB;
>  #ifdef CONFIG_SB1_PASS_1_WORKAROUNDS

* Daniel Jacobowitz <dan@debian.org> [2005-10-03 09:15]:
> > >  Well, the flag is not really to specify whether the common code is to be 
> > > used or not.  It's about whether the TLB is like that of the R4k.  
> > > Actually it's always been a mystery for me why the common code cannot be 
> > > used for the SB1, but perhaps there is something specific that I could 
> > > only discover in that "SB-1 Core User Manual" that I yet have to see, 
> > > sigh...
> > >  Of course if your TLB is indeed different from that of the R4k, then you 
> > > shouldn't be setting cp0.config.mt to 1 in the first place...
> > The reason was primarily the tiny bit of extra performance because the
> > SB1 doesn't need the hazard handling overhead.  Also tlb-sb1 has a few
> > changes that are needed to initialize a TLB in undefined state after
> > powerup.  That was needed to run Linux on firmware-less SB1 cores.
> FYI, all I have is a piece of hard evidence: this patch was the
> difference between not booting and booting for a Sentosa with CFE. 
> Which isn't firmwareless and isn't a tiny bit of extra performance
> issue.
> 
> I'll try to give CVS HEAD a shot this week sometime.

* Maciej W. Rozycki <macro@linux-mips.org> [2005-10-03 14:35]:
> > FYI, all I have is a piece of hard evidence: this patch was the
> > difference between not booting and booting for a Sentosa with CFE. 
> > Which isn't firmwareless and isn't a tiny bit of extra performance
> > issue.
>  Actually workarounds have been floating around for some time. ;-)  But 
> I'm glad this has now been fixed properly.

There was some discussion regarding this patch but no real conclusion.
Is it working without this patch now, or should it be applied (or
modified? - how?).
-- 
Martin Michlmayr
http://www.cyrius.com/

Re: [patch 1/5] SiByte fixes for 2.6.12

[Martin Michlmayr]

* Martin Michlmayr <tbm@cyrius.com> [2006-01-16 15:48]:
> There was some discussion regarding this patch but no real conclusion.
> Is it working without this patch now, or should it be applied (or
> modified? - how?).

Something like that is actually in git, so never mind.
-- 
Martin Michlmayr
http://www.cyrius.com/