> -----Original Message----- > From: Linux-nvdimm [mailto:linux-nvdimm-boun...@lists.01.org] On > Behalf Of Dave Jiang > Sent: Thursday, September 15, 2016 5:28 PM > To: vishal.l.ve...@intel.com > Cc: linux-nvdimm@lists.01.org > Subject: [PATCH] ndctl: move test/dax-errors buffer to global to > avoid gcc optimization > > Some gcc toolchain are optimizing out the memcpy and this causes dax- > errors > to not trigger the SIG_BUS when doing memcpy on an mmap'd buffer. By > moving > the buffer to a global variable this bypasses the optimization and > allow > the test to work as intended. > > Signed-off-by: Dave Jiang <dave.ji...@intel.com> > --- > test/dax-errors.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/test/dax-errors.c b/test/dax-errors.c > index 11d0031..9ea5c91 100644 > --- a/test/dax-errors.c > +++ b/test/dax-errors.c > @@ -17,6 +17,8 @@ > > static sigjmp_buf sj_env; > static int sig_count; > +/* buf is global in order to avoid gcc memcpy optimization */ > +static void *buf; > > static void sigbus_hdl(int sig, siginfo_t *siginfo, void *ptr) > { > @@ -27,7 +29,7 @@ static void sigbus_hdl(int sig, siginfo_t *siginfo, > void *ptr) > > static int test_dax_read_err(int fd) > { > - void *base, *buf; > + void *base; > int rc = 0; > > if (fd < 0) { >
I've run into that kind of problem before, and found that marking *buf as volatile (and leaving it inside the function) tends to be honored better by aggressive optimizing compilers and linkers. --- Robert Elliott, HPE Persistent Memory _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
