Messages in this thread | | | Date | Tue, 28 Feb 2017 09:57:25 -0800 | From | Guenter Roeck <> | Subject | Re: nios2 crash/hang in mainline due to 'lib: update LZ4 compressor module' |
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On Tue, Feb 28, 2017 at 04:53:31PM +0100, Tobias Klauser wrote: > (adding Sandra Loosemore to Cc due to possible relation to gcc/binutils > for nios2) > > On 2017-02-26 at 22:03:38 +0100, Guenter Roeck <linux@roeck-us.net> wrote: > > Hi Sven, > > > > my qemu test for nios2 started failing with commit 4e1a33b105dd ("lib: > > update LZ4 compressor module"). The test hangs early during boot before > > any console output is seen. Reverting the offending patch as well as the > > subsequent lz4 related patches fixes the problem. Disabling CONFIG_RD_LZ4 > > and with it other LZ4 options also fixes it (as does adding "return -EINVAL;" > > at the top of the LZ4 decompression code). For reference, bisect log > > is attached. > > > > I tried with buildroot toolchains using gcc 6.1.0 as well as 6.3.0 > > and binutils 2.26.1. Scripts used to run the tests are available at > > https://github.com/groeck/linux-build-test/tree/master/rootfs/nios2. > > Qemu is from qemu mainline or qemu v2.8 with nios2 patches applied. > > Looks like this is somehow related to gcc/binutils. Using GCC 4.8.3 and > binutils 2.24.51 (both from from Sourcery CodeBench Lite 2014.05) I can > get a kernel booting on latest master branch. AFAICT, none of the > LZ4_decompress_* functions are called during boot. > > However, using a self-built GCC 7.0 (20161127) and binutils 2.27 I can > reproduce the problem you see using the instructions Guenter provided in > the reply to Sven. > > I'll try to dig a bit deeper from here on. Any suggestions on what to > look out for wrt the differences between the gcc/binutils version are > welcome of course. >
I tried the following combinations of gcc and binutils: gcc 6.1.0; binutils 2.26.1 gcc 6.3.0; binutils 2.25.1 gcc 6.3.0; binutils 2.26.1 gcc 6.3.0; binutils 2.27
I used buildroot 2017.02-rc3 to build the toolchains. All have the problem.
Another data point, confirming what you say above: I am relatively (99%) sure that the code in question is not actually called. I added reference counters to make sure that this is the case. Just the existence of the LZ4 decompression code appears to be sufficient to cause the boot failure. Weird.
I just hope this only affects nios2.
Guenter
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