Re: [kvm-unit-tests PATCH v3 6/6] s390x: SMP test

[Thomas Huth <thuth@redhat.com>]

On 25/09/2019 15.27, David Hildenbrand wrote:
> On 20.09.19 10:03, Janosch Frank wrote:
>> Testing SIGP emulation for the following order codes:
>> * start
>> * stop
>> * restart
>> * set prefix
>> * store status
>> * stop and store status
>> * reset
>> * initial reset
>> * external call
>> * emegergency call
>>
>> restart and set prefix are part of the library and needed to start
>> other cpus.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  s390x/Makefile      |   1 +
>>  s390x/smp.c         | 242 ++++++++++++++++++++++++++++++++++++++++++++
>>  s390x/unittests.cfg |   4 +
>>  3 files changed, 247 insertions(+)
>>  create mode 100644 s390x/smp.c
>>
>> diff --git a/s390x/Makefile b/s390x/Makefile
>> index d83dd0b..3744372 100644
>> --- a/s390x/Makefile
>> +++ b/s390x/Makefile
>> @@ -15,6 +15,7 @@ tests += $(TEST_DIR)/cpumodel.elf
>>  tests += $(TEST_DIR)/diag288.elf
>>  tests += $(TEST_DIR)/stsi.elf
>>  tests += $(TEST_DIR)/skrf.elf
>> +tests += $(TEST_DIR)/smp.elf
>>  tests_binary = $(patsubst %.elf,%.bin,$(tests))
>>  
>>  all: directories test_cases test_cases_binary
>> diff --git a/s390x/smp.c b/s390x/smp.c
>> new file mode 100644
>> index 0000000..7032494
>> --- /dev/null
>> +++ b/s390x/smp.c
>> @@ -0,0 +1,242 @@
>> +/*
>> + * Tests sigp emulation
>> + *
>> + * Copyright 2019 IBM Corp.
>> + *
>> + * Authors:
>> + *    Janosch Frank <frankja@linux.ibm.com>
>> + *
>> + * This code is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2.
>> + */
>> +#include <libcflat.h>
>> +#include <asm/asm-offsets.h>
>> +#include <asm/interrupt.h>
>> +#include <asm/page.h>
>> +#include <asm/facility.h>
>> +#include <asm-generic/barrier.h>
>> +#include <asm/sigp.h>
>> +
>> +#include <smp.h>
>> +#include <alloc_page.h>
>> +
>> +static int testflag = 0;
>> +
>> +static void cpu_loop(void)
>> +{
>> +	for (;;) {}
> 
> Won't that be optimized out completely?

Why? AFAIK this is the standard way to write and endless loop ... how
can a compiler optimize that away?

 Thomas