Re: [PATCH 07/16] MIPS: Fix display memory size issue

[Youling Tang <tangyouling@xxxxxxxxxxx>]

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@xxxxxxxxxxx>
Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
---
 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).

Thanks,
Youling.

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