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Date: Mon, 20 Apr 2015 14:34:13 +0100
From: Yongbok Kim <yongbok.kim@imgtec.com>
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Subject: [Qemu-devel] running 64 bit user mode program on 32 bit host machine
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To: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Riku Voipio <riku.voipio@iki.fi>, Leon Alrae <leon.alrae@imgtec.com>, Richard Henderson <rth@twiddle.net>

Hi All,

I have faced a problem to run a simple 64 bit Linux user mode=20
application on
32 bit Linux host machines.
I did some investigation and found out that the TARGET_ELF_PAGESTART=20
macro in
the linux-user/elfload.c is causing the problem.
However I am not sure if this is the right solution as I am not familiar=20
with
the area.
Perhaps the macro should take care of target=E2=80=99s bits width rather =
than=20
just use
unsigned long.
Would you please confirm the change or suggest better solution?

Regards,
Yongbok


$  ../masterbin/mips64-linux-user/qemu-mips64 -cpu MIPS64R6-generic=20
./hello_linux.elf
qemu: uncaught target signal 11 (Segmentation fault) - core dumped
Segmentation fault (core dumped)


$ git diff
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 399c021..d99a43b 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1227,7 +1227,7 @@ struct exec

  /* Necessary parameters */
  #define TARGET_ELF_EXEC_PAGESIZE TARGET_PAGE_SIZE
-#define TARGET_ELF_PAGESTART(_v) ((_v) & ~(unsigned=20
long)(TARGET_ELF_EXEC_PAGESIZE-1))
+#define TARGET_ELF_PAGESTART(_v) ((_v) &=20
~(abi_ulong)(TARGET_ELF_EXEC_PAGESIZE-1))
  #define TARGET_ELF_PAGEOFFSET(_v) ((_v) & (TARGET_ELF_EXEC_PAGESIZE-1))

  #define DLINFO_ITEMS 14
(END)



WITH the change:
$  ../masterbin/mips64-linux-user/qemu-mips64 -cpu MIPS64R6-generic=20
./hello_linux.elf
Hello World!