[Crash-utility] [PATCH 07/16] MIPS: Fix display memory size issue

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> Hi, Vincent
> Thank you for your reply and suggestion.
> 
> 
> On 02/10/2021 09:59 PM, Vincent Whitchurch wrote:
> 
> 
> 	On Tue, Jan 26, 2021 at 12:13:31PM +0100, Youling Tang wrote:
> 
> 		"__node_data" instead of "node_data" is used in the MIPS architecture,
> 		so "__node_data" is used to replace "node_data" to improve the use of
> 		next_online_pgdat() functions in the MIPS architecture.
> 
> 
> 	On my 32-bit MIPS dumps, MEMORY: works properly without this patch, but
> 	they have contig_page_data instead of __node_data/node_data so they
> 
> When the node_data/__node_data and pgdat_list symbols cannot be successfully
> read from the kernel symbols, the contig_page_data symbol will be read. In
> your 32-bit machine, there should be no node_data/__node_data, pgdat_list
> symbols, and a single node, so the memory size can be displayed normally
> without this patch.
> 
> 
> 	shouldn't be affected by this code.  AFAICS only mach-loongson64 and
> 	mach-ip27 have __node_data.
> 
> 
> Yes, only mach-loongson64 and mach-ip27 use __node_data in the MIPS
> architecture.
> 
> 
> 
> 		E.g. Without this patch:
> 		...
> 		MEMORY: 0
> 		...
> 
> 
> 		With this patch:
> 		...
> 		MEMORY: 7.5 GB
> 		...
> 
> 		Signed-off-by: Huacai Chen <chenhuacai at loongson.cn> <mailto:chenhuacai at loongson.cn>
> 		Signed-off-by: Youling Tang <tangyouling at loongson.cn> <mailto:tangyouling at loongson.cn>
> 		---
> 		 memory.c | 28 ++++++++++++++++++----------
> 		 1 file changed, 18 insertions(+), 10 deletions(-)
> 
> 		diff --git a/memory.c b/memory.c
> 		index 33b0ca7..5347958 100644
> 		--- a/memory.c
> 		+++ b/memory.c
> 		@@ -17820,22 +17820,28 @@ next_online_pgdat(int node)
> 		         char buf[BUFSIZE];
> 		 	ulong pgdat;
> 
> 		+#ifndef __mips__
> 		+#define NODE_DATA_VAR "node_data"
> 		+#else
> 		+#define NODE_DATA_VAR "__node_data"
> 		+#endif
> 
> 
> 	Is this really correct?  Doesn't __mips__ check the host architecture
> 	when what we want to check here is the target?
> 
> The results of filtering in the kernel code are as follows :
> # grep -wnr "EXPORT_SYMBOL(node_data)"
> arch/alpha/mm/numa.c:23:EXPORT_SYMBOL(node_data);
> arch/arc/mm/init.c:37:EXPORT_SYMBOL(node_data);
> arch/sparc/mm/init_64.c:1106:EXPORT_SYMBOL(node_data);
> arch/powerpc/mm/numa.c:52:EXPORT_SYMBOL(node_data);
> arch/s390/kernel/numa.c:18:EXPORT_SYMBOL(node_data);
> arch/arm64/mm/numa.c:20:EXPORT_SYMBOL(node_data);
> arch/x86/mm/numa.c:26:EXPORT_SYMBOL(node_data);
> 
> # grep -wnr "EXPORT_SYMBOL(__node_data)"
> arch/mips/sgi-ip27/ip27-memory.c:38:EXPORT_SYMBOL(__node_data);
> arch/mips/loongson64/numa.c:33:EXPORT_SYMBOL(__node_data);
> 
> 
> In the MIPS architecture, no platform uses node_data, only the __node_data
> symbol. All other architectures use node_data symbols, so it should be
> feasible to use __mips__ to determine the target (as long as it is a MIPS
> architecture, use __node_data instead of node_data).

OK.  Could you add a code comment about this to avoid confusion?

Thanks,
Kazu