[PATCH] export htab value for kexec on non-lpar

[R Sharada]

Hello,
	kexec on ppc64 requires that we be able to identify and avoid 
having valid segment destination addresses in the htab area, on non-lpar 
machines, as kexec uses the page tables (copy_page) for copying into the final
destination addresses. On non-lpar power4 machines, this means that the 
kexec-tools needs to have a way to know where the htab addresses lie. 

Here is a patch to export the htab details into /proc/device-tree under /chosen
node. Created and tested against 2.6.13-rc6.

Kindly review and let me know if there are any issues in getting this accepted.

Thanks and Regards,
Sharada

---


diff -puN ./arch/ppc64/kernel/setup.c~kexec-export-htab-value ./arch/ppc64/kernel/setup.c
--- linux-2.6.13-rc6/./arch/ppc64/kernel/setup.c~kexec-export-htab-value	2005-08-23 18:27:14.000000000 +0530
+++ linux-2.6.13-rc6-sharada/./arch/ppc64/kernel/setup.c	2005-08-23 18:34:11.000000000 +0530
@@ -59,12 +59,19 @@
 #include <asm/lmb.h>
 #include <asm/iSeries/ItLpNaca.h>
 
+#include <linux/bootmem.h>
+
 #ifdef DEBUG
 #define DBG(fmt...) udbg_printf(fmt)
 #else
 #define DBG(fmt...)
 #endif
 
+#ifdef CONFIG_KEXEC
+#define HASH_GROUP_SIZE 0x80    /* size of each hash group, asm/mmu.h */
+void export_htab_value(void);
+#endif
+
 /*
  * Here are some early debugging facilities. You can enable one
  * but your kernel will not boot on anything else if you do so
@@ -1086,6 +1093,9 @@ void __init setup_arch(char **cmdline_p)
 	}
 
 	paging_init();
+#ifdef CONFIG_KEXEC
+	export_htab_value();
+#endif
 	ppc64_boot_msg(0x15, "Setup Done");
 }
 
@@ -1358,3 +1368,39 @@ void cpu_die(void)
 	if (ppc_md.cpu_die)
 		ppc_md.cpu_die();
 }
+
+#ifdef CONFIG_KEXEC
+void export_htab_value()
+{
+	struct device_node *node;
+	struct property *newprop1, *newprop2;
+	unsigned long low, high;
+
+	if (systemcfg->platform != PLATFORM_PSERIES_LPAR) {
+		node = of_find_node_by_path("/chosen");
+		if (!node)
+			return;
+		newprop1 = alloc_bootmem(sizeof(struct property) + sizeof(unsigned long));
+		if (newprop1 == NULL)
+			return;
+		newprop2 = alloc_bootmem(sizeof(struct property) + sizeof(unsigned long));
+		if (newprop1 == NULL)
+			return;
+		memset(newprop1, 0, sizeof(struct property));
+		memset(newprop2, 0, sizeof(struct property));
+		newprop1->name = "htab_address";
+		newprop1->length = sizeof(unsigned long);
+		newprop1->value = (unsigned char *)&newprop1[1];
+		low = __pa(htab_address);
+		memcpy(newprop1->value, &low, sizeof(low));
+		prom_add_property(node, newprop1);
+		newprop2->name = "htab_size";
+		newprop2->length = sizeof(unsigned long);
+		newprop2->value = (unsigned char *)&newprop2[1];
+		high = low + (htab_hash_mask + 1) * HASH_GROUP_SIZE;
+		memcpy(newprop2->value, &high, sizeof(high));
+		prom_add_property(node, newprop2);
+		of_node_put(node);
+	}
+}
+#endif
_