can't boot mpc5200, powerpc: Enable AT_BASE_PLATFORM aux vector

I've lost my ability to boot on the mpc5200. Reverting this patch fixes it.

powerpc: Enable AT_BASE_PLATFORM aux vector
9115d13453dee22473a1e8cacc90a8d64a9c4bc9

commit 9115d13453dee22473a1e8cacc90a8d64a9c4bc9
Author: Nathan Lynch [off-list ref]
Date:   Wed Jul 16 09:58:51 2008 +1000

    powerpc: Enable AT_BASE_PLATFORM aux vector

    Stash the first platform string matched by identify_cpu() in
    powerpc_base_platform, and supply that to the ELF loader for the value
    of AT_BASE_PLATFORM.

    Signed-off-by: Nathan Lynch [off-list ref]
    Signed-off-by: Benjamin Herrenschmidt [off-list ref]

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index b936a1d..25a052c 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c

@@ -23,6 +23,9 @@
 struct cpu_spec* cur_cpu_spec = NULL;
 EXPORT_SYMBOL(cur_cpu_spec);

+/* The platform string corresponding to the real PVR */
+const char *powerpc_base_platform;
+
 /* NOTE:
  * Unlike ppc32, ppc64 will only call this once for the boot CPU, it's
  * the responsibility of the appropriate CPU save/restore functions to

@@ -1652,6 +1655,14 @@ struct cpu_spec * __init identify_cpu(unsigned

long offset, unsigned int pvr)
 			} else
 				*t = *s;
 			*PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
+
+			/*
+			 * Set the base platform string once; assumes
+			 * we're called with real pvr first.
+			 */
+			if (powerpc_base_platform == NULL)
+				powerpc_base_platform = t->platform;
+
 #if defined(CONFIG_PPC64) || defined(CONFIG_BOOKE)
 			/* ppc64 and booke expect identify_cpu to also call
 			 * setup_cpu for that processor. I will consolidate

diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index 2a3e907..ef8a248 100644
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h

@@ -127,6 +127,8 @@ extern struct cpu_spec *identify_cpu(unsigned long

offset, unsigned int pvr);
 extern void do_feature_fixups(unsigned long value, void *fixup_start,
 			      void *fixup_end);

+extern const char *powerpc_base_platform;
+
 #endif /* __ASSEMBLY__ */

 /* CPU kernel features */

diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h
index 8966467..80d1f39 100644
--- a/include/asm-powerpc/elf.h
+++ b/include/asm-powerpc/elf.h

@@ -217,6 +217,14 @@ typedef elf_vrregset_t elf_fpxregset_t;

 #define ELF_PLATFORM	(cur_cpu_spec->platform)

+/* While ELF_PLATFORM indicates the ISA supported by the platform, it
+ * may not accurately reflect the underlying behavior of the hardware
+ * (as in the case of running in Power5+ compatibility mode on a
+ * Power6 machine).  ELF_BASE_PLATFORM allows ld.so to load libraries
+ * that are tuned for the real hardware.
+ */
+#define ELF_BASE_PLATFORM (powerpc_base_platform)
+
 #ifdef __powerpc64__
 # define ELF_PLAT_INIT(_r, load_addr)	do {	\
 	_r->gpr[2] = load_addr; 		\

-- 
Jon Smirl
jonsmirl@gmail.com

Jon Smirl wrote:

I've lost my ability to boot on the mpc5200. Reverting this patch fixes it.

How does it fail?

Hmm, maybe this needs RELOC/PTRRELOC tricks?

On Fri, 2008-07-25 at 17:00 -0500, Nathan Lynch wrote:

Jon Smirl wrote:

quoted

I've lost my ability to boot on the mpc5200. Reverting this patch fixes it.

How does it fail?

quoted

@@ -1652,6 +1655,14 @@ struct cpu_spec * __init identify_cpu(unsigned

long offset, unsigned int pvr)
 			} else
 				*t = *s;
 			*PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
+
+			/*
+			 * Set the base platform string once; assumes
+			 * we're called with real pvr first.
+			 */
+			if (powerpc_base_platform == NULL)
+				powerpc_base_platform = t->platform;
+

Hmm, maybe this needs RELOC/PTRRELOC tricks?

Hrm... indeed.

if (RELOC(powerpc_base_platform))
	RELOC(powerpc_base_platform) = t->platform;

try that.

Ben.

On 7/25/08, Benjamin Herrenschmidt [off-list ref] wrote:

On Fri, 2008-07-25 at 17:00 -0500, Nathan Lynch wrote:
 > Jon Smirl wrote:
 > > I've lost my ability to boot on the mpc5200. Reverting this patch fixes it.
 >
 > How does it fail?
 >
 >
 > > @@ -1652,6 +1655,14 @@ struct cpu_spec * __init identify_cpu(unsigned
 > > long offset, unsigned int pvr)
 > >                     } else
 > >                             *t = *s;
 > >                     *PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
 > > +
 > > +                   /*
 > > +                    * Set the base platform string once; assumes
 > > +                    * we're called with real pvr first.
 > > +                    */
 > > +                   if (powerpc_base_platform == NULL)
 > > +                           powerpc_base_platform = t->platform;
 > > +
 >
 > Hmm, maybe this needs RELOC/PTRRELOC tricks?


Hrm... indeed.

 if (RELOC(powerpc_base_platform))
        RELOC(powerpc_base_platform) = t->platform;

It completely fails booting, no console or anything.

Where is RELOC defined, prom_init.c?

#ifdef CONFIG_PPC64
#define RELOC(x)        (*PTRRELOC(&(x)))
#define ADDR(x)         (u32) add_reloc_offset((unsigned long)(x))
#define OF_WORKAROUNDS  0
#else
#define RELOC(x)        (x)
#define ADDR(x)         (u32) (x)
#define OF_WORKAROUNDS  of_workarounds
int of_workarounds;
#endif

 try that.

 Ben.

-- 
Jon Smirl
jonsmirl@gmail.com

On 7/25/08, Jon Smirl [off-list ref] wrote:

On 7/25/08, Benjamin Herrenschmidt [off-list ref] wrote:
 > On Fri, 2008-07-25 at 17:00 -0500, Nathan Lynch wrote:
 >  > Jon Smirl wrote:
 >  > > I've lost my ability to boot on the mpc5200. Reverting this patch fixes it.
 >  >
 >  > How does it fail?
 >  >
 >  >
 >  > > @@ -1652,6 +1655,14 @@ struct cpu_spec * __init identify_cpu(unsigned
 >  > > long offset, unsigned int pvr)
 >  > >                     } else
 >  > >                             *t = *s;
 >  > >                     *PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
 >  > > +
 >  > > +                   /*
 >  > > +                    * Set the base platform string once; assumes
 >  > > +                    * we're called with real pvr first.
 >  > > +                    */
 >  > > +                   if (powerpc_base_platform == NULL)
 >  > > +                           powerpc_base_platform = t->platform;
 >  > > +
 >  >
 >  > Hmm, maybe this needs RELOC/PTRRELOC tricks?
 >
 >
 > Hrm... indeed.
 >
 >  if (RELOC(powerpc_base_platform))
 >         RELOC(powerpc_base_platform) = t->platform;

This boots:

#define RELOC(x)        (*PTRRELOC(&(x)))
			if (RELOC(powerpc_base_platform))
			       RELOC(powerpc_base_platform) = t->platform;

It completely fails booting, no console or anything.

 Where is RELOC defined, prom_init.c?

 #ifdef CONFIG_PPC64
 #define RELOC(x)        (*PTRRELOC(&(x)))
 #define ADDR(x)         (u32) add_reloc_offset((unsigned long)(x))
 #define OF_WORKAROUNDS  0
 #else
 #define RELOC(x)        (x)
 #define ADDR(x)         (u32) (x)
 #define OF_WORKAROUNDS  of_workarounds
 int of_workarounds;
 #endif



 >
 >  try that.
 >
 >  Ben.

quoted

 >
 >


 --
 Jon Smirl
 jonsmirl@gmail.com

-- 
Jon Smirl
jonsmirl@gmail.com

Commit 9115d13453dee22473a1e8cacc90a8d64a9c4bc9 ("powerpc: Enable
AT_BASE_PLATFORM aux vector") broke boot on 32-bit powerpc systems; we
have to use PTRRELOC to initialize powerpc_base_platform this early in
boot.

Bug reported by Jon Smirl.

Signed-off-by: Nathan Lynch <redacted>
---
Benjamin Herrenschmidt wrote:

if (RELOC(powerpc_base_platform))
	RELOC(powerpc_base_platform) = t->platform;

try that.

Maybe this?  (RELOC isn't defined in any header AFAICT).

 arch/powerpc/kernel/cputable.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 25a052c..25c273c 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c

@@ -1660,8 +1660,8 @@ struct cpu_spec * __init identify_cpu(unsigned long offset, unsigned int pvr)
 			 * Set the base platform string once; assumes
 			 * we're called with real pvr first.
 			 */
-			if (powerpc_base_platform == NULL)
-				powerpc_base_platform = t->platform;
+			if (*PTRRELOC(&powerpc_base_platform) == NULL)
+				*PTRRELOC(&powerpc_base_platform) = t->platform;
 
 #if defined(CONFIG_PPC64) || defined(CONFIG_BOOKE)
 			/* ppc64 and booke expect identify_cpu to also call

-- 
1.5.6.2

On 7/25/08, Nathan Lynch [off-list ref] wrote:

This works too.

  #if defined(CONFIG_PPC64) || defined(CONFIG_BOOKE)
                        /* ppc64 and booke expect identify_cpu to also call

--
 1.5.6.2
 _______________________________________________
 Linuxppc-dev mailing list
 Linuxppc-dev@ozlabs.org
 https://ozlabs.org/mailman/listinfo/linuxppc-dev

-- 
Jon Smirl
jonsmirl@gmail.com

This works too.

Thanks Jon, sorry about that.