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

To: Linux MIPS Mailing List <>
Subject: Commit 597ce1723 (MIPS: Support for 64-bit FP with O32 binaries) causing qemu hang with mips64 kernels
From: Guenter Roeck <>
Date: Fri, 07 Feb 2014 19:39:26 -0800
Cc: Paul Burton <>, Ralf Baechle <>, "" <>
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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 seem
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 provide
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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