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Re: Commit 597ce1723 (MIPS: Support for 64-bit FP with O32 binaries) cau

To: Huacai Chen <>
Subject: Re: Commit 597ce1723 (MIPS: Support for 64-bit FP with O32 binaries) causing qemu hang with mips64 kernels
From: Guenter Roeck <>
Date: Mon, 24 Feb 2014 20:13:33 -0800
Cc: Linux MIPS Mailing List <>, Paul Burton <>, Ralf Baechle <>, "" <>
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On 02/07/2014 08:55 PM, Guenter Roeck wrote:
On 02/07/2014 07:57 PM, Huacai Chen wrote:

Maybe you can try this:

With those two patches applied the problem is gone.

Any idea if and when those patches may find their way upstream ?
3.14-rc4 still has the problem.


Thanks a lot!


On Sat, Feb 8, 2014 at 11:39 AM, Guenter Roeck <> wrote:

Hi all,

in 3.14-rc1, my mips64 qemu test fails. The image boots and then hangs.
Bisect points to commit 597ce1723 (MIPS: Support for 64-bit FP with O32
Reverting this commit fixes the problem. Disabling MIPS_O32_FP64_SUPPORT
in my test image does _not_ solve the problem. The qemu version does not
to make a difference; I tested with qemu 1.6.0 and 1.7.0.

Console log output is available in

When the problem is seen, the emulation hangs as can be seen in the log,
and the qemu process consumes 100% CPU until it is killed.

qemu command line is

qemu-system-mips64 -kernel vmlinux -M malta -hda
core-image-minimal-qemumips64.ext3 \
-vga cirrus -usb -usbdevice wacom-tablet -no-reboot -m 128 --append
"root=/dev/hda \
rw mem=128M console=ttyS0 console=tty" -nographic

The same configuration works fine with earlier kernels. I'll be happy to
the detailed configuration as well as the root file system for testing if

Obviously I have no idea if this is a problem with the patch or with qemu.
If there is anything I can do to help tracking down the problem further,
please let me know.


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