Re: [Crash-utility] [PATCH] CONFIG_SPARSEMEM for s390(x)
Michael Holzheu wrote:
Hi Dave,
Here the new patch.
Unfortunately kmem -n reports an error...
crash> kmem -n
NODE SIZE PGLIST_DATA BOOTMEM_DATA NODE_ZONES
0 131071 4c9100 90c158 4c9100
4cd800
4d1f00
MEM_MAP START_PADDR START_MAPNR
3e040000000 0 0
ZONE NAME SIZE MEM_MAP START_PADDR START_MAPNR
0 DMA 131071 3e040000000 0 0
1 Normal 0 0 0 0
2 Movable 0 0 0 0
-------------------------------------------------------------------
NR SECTION CODED_MEM_MAP MEM_MAP PFN
0 a3a800 3e040000000 3e040000000
0
1 a3a810 3e040000000 3e040580000
65536
kmem: read error: kernel virtual address: 0 type: "memory section"
My guess is that it might have something to do with the zero-based kernel
virtual address space on s390/s390x.
I also guess that the trail would have been:
cmd_kmem
dump_memory_nodes
dump_mem_sections
section_mem_map_addr
read_mem_section
where read_mem_section() can legitimately return if the addr
passed is not kernel virtual address of a mem_section structure:
char *
read_mem_section(ulong addr)
{
if (!IS_KVADDR(addr))
return 0;
readmem(addr, KVADDR, vt->mem_section, SIZE(mem_section),
"memory section", FAULT_ON_ERROR);
return vt->mem_section;
}
But the s390/s390x implementation of IS_KVADDR() accepts a kernel
virtual address of zero. It tries to read it and craps out.
I note that the kernel has this:
static inline int valid_section(struct mem_section *section)
{
return (section && (section->section_mem_map &
SECTION_MARKED_PRESENT));
}
which requires a non-zero section address for all arches. I'm thinking that
if you make read_mem_section() above return 0 if addr is zero, then it might
fix it?
Dave
---
diff -Naurp crash-4.0-7.1/defs.h crash-4.0-7.1-sparse-mem-s390/defs.h
--- crash-4.0-7.1/defs.h 2008-08-19 17:10:51.000000000 +0200
+++ crash-4.0-7.1-sparse-mem-s390/defs.h 2008-09-04 18:24:10.000000000 +0200
@@ -2636,6 +2636,9 @@ struct efi_memory_desc_t {
#define TIF_SIGPENDING (2)
+#define _SECTION_SIZE_BITS 25
+#define _MAX_PHYSMEM_BITS 31
+
#endif /* S390 */
#ifdef S390X
@@ -2658,6 +2661,9 @@ struct efi_memory_desc_t {
#define TIF_SIGPENDING (2)
+#define _SECTION_SIZE_BITS 28
+#define _MAX_PHYSMEM_BITS 42
+
#endif /* S390X */
#ifdef PLATFORM
diff -Naurp crash-4.0-7.1/s390.c crash-4.0-7.1-sparse-mem-s390/s390.c
--- crash-4.0-7.1/s390.c 2008-08-19 17:10:51.000000000 +0200
+++ crash-4.0-7.1-sparse-mem-s390/s390.c 2008-09-04 18:24:27.000000000 +0200
@@ -130,11 +130,14 @@ s390_init(int when)
machdep->dump_irq = s390_dump_irq;
if (!machdep->hz)
machdep->hz = HZ;
+ machdep->section_size_bits = _SECTION_SIZE_BITS;
+ machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
break;
case POST_INIT:
break;
}
+
}
/*
diff -Naurp crash-4.0-7.1/s390x.c crash-4.0-7.1-sparse-mem-s390/s390x.c
--- crash-4.0-7.1/s390x.c 2008-08-19 17:10:51.000000000 +0200
+++ crash-4.0-7.1-sparse-mem-s390/s390x.c 2008-09-04 18:24:24.000000000 +0200
@@ -128,6 +128,8 @@ s390x_init(int when)
machdep->dump_irq = s390x_dump_irq;
if (!machdep->hz)
machdep->hz = HZ;
+ machdep->section_size_bits = _SECTION_SIZE_BITS;
+ machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
break;
case POST_INIT:
--
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