Two "bugletts" on SPARC 64 @ kernel 2.4

Two "bugletts" on SPARC 64 @ kernel 2.4

[Jurzitza, Dieter]

Dear listmembers,
please find attached two small patches against kernel 2.4.33 for (at least) SPARC 64:

--- linux/include/linux/module.h	2004-12-15 08:34:44.000000000 +0100
+++ linux/include/linux/module.h	2004-12-15 08:45:32.000000000 +0100
@@ -31,7 +31,11 @@
 /* Used by get_kernel_syms, which is obsolete.  */
 struct kernel_sym
 {
-	unsigned long value;
+#ifdef __ARCH_SPARC64_ATOMIC__
+	  unsigned int value;
+#else
+          unsigned long value;
+#endif
 	char name[60];		/* should have been 64-sizeof(long); oh well */
 };
 
--- linux/arch/sparc64/kernel/sparc64_ksyms.c.original	2005-11-16 20:12:54.000000000 +0100
+++ linux/arch/sparc64/kernel/sparc64_ksyms.c	2006-08-14 12:55:48.000000000 +0200
@@ -357,6 +357,7 @@
 EXPORT_SYMBOL_NOVERS(__ret_efault);
 
 /* No version information on these, as gcc produces such symbols. */
+EXPORT_SYMBOL_NOVERS(memchr);
 EXPORT_SYMBOL_NOVERS(memcmp);
 EXPORT_SYMBOL_NOVERS(memcpy);
 EXPORT_SYMBOL_NOVERS(memset);
--- linux/arch/sparc/kernel/sparc_ksyms.c.original	2006-08-14 12:59:04.000000000 +0200
+++ linux/arch/sparc/kernel/sparc_ksyms.c	2006-08-14 12:59:04.000000000 +0200
@@ -293,6 +293,7 @@
 EXPORT_SYMBOL_NOVERS(__ret_efault);
 
 /* No version information on these, as gcc produces such symbols. */
+EXPORT_SYMBOL_NOVERS(memchr);
 EXPORT_SYMBOL_NOVERS(memcmp);
 EXPORT_SYMBOL_NOVERS(memcpy);
 EXPORT_SYMBOL_NOVERS(memset);


1.) due to the fact that sizeof(unsigned long) is larger on SPARC 64 (8 byte vs. 4 byte) than on some other architectures, the size of the structure kernel_sym grows accordingly. This results in the fact that on SPARC 64 less many kernel syms may be read by get_kernel_syms() than on other architectures due to the limitation in memory available. On 32-bit arches sizeof(kernel_sym) is 64. On SPARC64 it is initially 68, due to the need for word alignment we end up at 72 Byte per struct. Therefore we can read 2048 structs of type kernel_sym on x32 in contrast to only 1820 structs on SPARC64. The define shown above replacing the unsigned long by an unsigned int in case of SPARC64 fixes this (without any harm).

2.) with kernel 2.4.33 the call to memcpy has been introduced in the smbfs-module. Because there is no native function for this on SPARC, one needs to EXPORT_SYM_NOVERS for this (TX to Dave Miller who helped me finding this out). To avoid unneccessary questions on this issue the patch above is mentioned.

Take care



Dieter Jurzitza


-- 
________________________________________________

HARMAN BECKER AUTOMOTIVE SYSTEMS

Dr.-Ing. Dieter Jurzitza
Manager Hardware Systems
   System Development

Industriegebiet Ittersbach
Becker-Göring Str. 16
D-76307 Karlsbad / Germany

Phone: +49 (0)7248 71-1577
Fax:   +49 (0)7248 71-1216
eMail: DJurzitza@harmanbecker.com
Internet: http://www.becker.de
 


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Re: Two "bugletts" on SPARC 64 @ kernel 2.4

[David Miller]

From: "Jurzitza, Dieter" <DJurzitza@harmanbecker.com>
Date: Mon, 21 Aug 2006 13:37:51 +0200

> --- linux/include/linux/module.h	2004-12-15 08:34:44.000000000 +0100
> +++ linux/include/linux/module.h	2004-12-15 08:45:32.000000000 +0100
> @@ -31,7 +31,11 @@
>  /* Used by get_kernel_syms, which is obsolete.  */
>  struct kernel_sym
>  {
> -	unsigned long value;
> +#ifdef __ARCH_SPARC64_ATOMIC__
> +	  unsigned int value;
> +#else
> +          unsigned long value;
> +#endif
>  	char name[60];		/* should have been 64-sizeof(long); oh well */
>  };

1) You should post sparc patches at least CC:'d to sparclinux@vger.kernel.org
   which is where the Sparc developers hang out.

2) I can't see any reason why this part of your patch can be valid.
   This structure is exported to userspace and therefor is part of
   the user-visible API and thus cannot be changed.

If there is some bug or bogus limitation in the module tools which
limits the number of symbols visible due to the sizing of this
structure, that is what needs to be changed not this structure.