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Re: [Qemu-devel] [PATCH v3 10/11] tcg-mips: Adjust qemu_ld/st for mips64
From: |
Jin Guojie |
Subject: |
Re: [Qemu-devel] [PATCH v3 10/11] tcg-mips: Adjust qemu_ld/st for mips64 |
Date: |
Mon, 28 Nov 2016 14:59:08 +0800 |
In Richard's v2 patch (shown as below), the compilation on mips64 host is
disabled.
-#define LO_OFF (MIPS_BE * 4)
-#define HI_OFF (4 - LO_OFF)
+#if TCG_TARGET_REG_BITS == 32
+# define LO_OFF (MIPS_BE * 4)
+# define HI_OFF (4 - LO_OFF)
+#else
+extern int link_error(void);
+# define LO_OFF link_error()
+# define HI_OFF link_error()
+#endif
When I compiled this patch on Loongson as mips64el, a link error occured:
LINK i386-softmmu/qemu-system-i386
tcg/tcg.o: In function `tcg_out_tlb_load':
tcg-target.inc.c:1252: undefined reference to `link_error'
To pass the compilation, I removed the link_error() and redefined
LO_OFF/HI_OFF.
It works OK on little-endian mips o32/n64 host. I have no big-endian mips
machine,
so the bug on big-endian is not discovered.
Frankly speaking, I didn't take n32 into consideration until you pointed out
that.
I feel that n32 is rarely used in current and future market. I can not even
find an n32
debian distribution in Aurelien's qemu image collection.
How about leave n32 as a TODO feature?
Jin Guojie
------------------ Original ------------------
From: "Richard Henderson";<address@hidden>;
Date: Nov 25, 2016
To: "Jin Guojie"<address@hidden>; "qemu-devel"<address@hidden>;
Cc: "Aurelien Jarno"<address@hidden>; "James Hogan"<address@hidden>;
Subject: Re: [PATCH v3 10/11] tcg-mips: Adjust qemu_ld/st for mips64
On 11/25/2016 04:31 AM, Jin Guojie wrote:
> -#define LO_OFF (MIPS_BE * 4)
> -#define HI_OFF (4 - LO_OFF)
> +# define LO_OFF (MIPS_BE * sizeof(long))
> +# define HI_OFF (sizeof(long) - LO_OFF)
For n32, sizeof(long) == 4, and for n64, sizeof(long) == 8. So in the end this
change must be wrong for big-endian.
Surely using link_error, as my patch did, to assert at compile-time that these
values were never used for TCG_TARGET_REGS == 64 is better.
r~
- Re: [Qemu-devel] [PATCH v3 10/11] tcg-mips: Adjust qemu_ld/st for mips64,
Jin Guojie <=