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authorNathan Rossi <nathan.rossi@xilinx.com>2014-01-21 17:36:23 +1000
committerNathan Rossi <nathan.rossi@xilinx.com>2014-01-21 17:36:23 +1000
commit323553ac983c6cbcaf586c9ab554f2e08ae215eb (patch)
tree5c0147a2643e8ba69cc516c6fecea90b73cce6d4 /README
parent17972404d1fb54e2d6657a897d7f94a272abdabe (diff)
downloadmeta-xilinx-323553ac983c6cbcaf586c9ab554f2e08ae215eb.tar.gz
README: Remove resolved MicroBlaze known issue
* The "MicroBlaze Linux Kernel 3.8+ and GCC 4.8+ fails to boot" issue has been resolved Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
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@@ -82,27 +82,6 @@ Booting
82Please see the associated README file for each avaliable boot method in the 82Please see the associated README file for each avaliable boot method in the
83'docs/BOOT.*' files of this layer. 83'docs/BOOT.*' files of this layer.
84 84
85Known Issues
86============
87
88MicroBlaze Linux Kernel 3.8+ and GCC 4.8+ fails to boot
89-------------------------------------------------------
90There is a regression in GCC 4.8 that causes a race condition in the kernel. It
91occurs due to changes in the optimization and improper handling of certain
92branch optimization where delay slots are used.
93
94The error during kernel boot looks similar to:
95 ------------[ cut here ]------------
96 WARNING: at mm/mmap.c:2657 exit_mmap+0x158/0x178()
97
98There are two work arounds for this issue, the first which is recommended is to
99use the MicroBlaze external toolchain that is provided by Xilinx SDK or
100PetaLinux.
101
102The the second workaround applies to the linux-xlnx only, disable the kernel
103configuration "CONFIG_OPTIMIZE_FOR_SIZE". This prevents the compiler from trying
104to optimize the delay slots incorrectly.
105
106Configuring External Toolchain 85Configuring External Toolchain
107============================== 86==============================
108 87