Re: [kvm-unit-tests RFC 1/2] s390x: Add guest snippet support

[Thomas Huth <thuth@redhat.com>]

On 21/06/2021 14.19, Janosch Frank wrote:
> On 6/21/21 12:10 PM, Thomas Huth wrote:
>> On 20/05/2021 11.47, Janosch Frank wrote:
>>> Snippets can be used to easily write and run guest (SIE) tests.
>>> The snippet is linked into the test binaries and can therefore be
>>> accessed via a ptr.
>>>
>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>> ---
>>>    .gitignore                |  2 ++
>>>    s390x/Makefile            | 28 ++++++++++++++++++---
>>>    s390x/snippets/c/cstart.S | 13 ++++++++++
>>>    s390x/snippets/c/flat.lds | 51 +++++++++++++++++++++++++++++++++++++++
>>>    4 files changed, 91 insertions(+), 3 deletions(-)
>>>    create mode 100644 s390x/snippets/c/cstart.S
>>>    create mode 100644 s390x/snippets/c/flat.lds
>>>
>>> diff --git a/.gitignore b/.gitignore
>>> index 784cb2dd..29d3635b 100644
>>> --- a/.gitignore
>>> +++ b/.gitignore
>>> @@ -22,3 +22,5 @@ cscope.*
>>>    /api/dirty-log
>>>    /api/dirty-log-perf
>>>    /s390x/*.bin
>>> +/s390x/snippets/*/*.bin
>>> +/s390x/snippets/*/*.gbin
>>> diff --git a/s390x/Makefile b/s390x/Makefile
>>> index 8de926ab..fe267011 100644
>>> --- a/s390x/Makefile
>>> +++ b/s390x/Makefile
>>> @@ -75,11 +75,33 @@ OBJDIRS += lib/s390x
>>>    asmlib = $(TEST_DIR)/cstart64.o $(TEST_DIR)/cpu.o
>>>    
>>>    FLATLIBS = $(libcflat)
>>> -%.elf: %.o $(FLATLIBS) $(SRCDIR)/s390x/flat.lds $(asmlib)
>>> +
>>> +SNIPPET_DIR = $(TEST_DIR)/snippets
>>> +
>>> +# C snippets that need to be linked
>>> +snippets-c =
>>> +
>>> +# ASM snippets that are directly compiled and converted to a *.gbin
>>> +snippets-a =
>>
>> Could you please call this snippets-s instead of ...-a ? The -a suffix looks
>> like an archive to me otherwise.
> 
> Sure
> 
>>
>>> +snippets = $(snippets-a)$(snippets-c)
>>
>> Shouldn't there be a space between the two?
> 
> Yes, already fixed that a long while ago
> I thought I had sent out a new version already, maybe that was an
> illusion as I can't seem to find it right now.
> 
>>
>>> +snippets-o += $(patsubst %.gbin,%.o,$(snippets))
>>> +
>>> +$(snippets-a): $(snippets-o) $(FLATLIBS)
>>> +	$(OBJCOPY) -O binary $(patsubst %.gbin,%.o,$@) $@
>>> +	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
>>> +
>>> +$(snippets-c): $(snippets-o) $(SNIPPET_DIR)/c/cstart.o  $(FLATLIBS)
>>> +	$(CC) $(LDFLAGS) -o $@ -T $(SNIPPET_DIR)/c/flat.lds \
>>> +		$(filter %.o, $^) $(FLATLIBS)
>>> +	$(OBJCOPY) -O binary $@ $@
>>> +	$(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $@ $@
>>> +
>>> +%.elf: $(snippets) %.o $(FLATLIBS) $(SRCDIR)/s390x/flat.lds $(asmlib)
>>>    	$(CC) $(CFLAGS) -c -o $(@:.elf=.aux.o) \
>>>    		$(SRCDIR)/lib/auxinfo.c -DPROGNAME=\"$@\"
>>>    	$(CC) $(LDFLAGS) -o $@ -T $(SRCDIR)/s390x/flat.lds \
>>> -		$(filter %.o, $^) $(FLATLIBS) $(@:.elf=.aux.o)
>>> +		$(filter %.o, $^) $(FLATLIBS) $(snippets) $(@:.elf=.aux.o)
>>
>> Does this link the snippets into all elf files? ... wouldn't it be better to
>> restrict it somehow to the files that really need them?
> 
> Yes it does.
> I'd like to avoid having to specify a makefile rule for every test that
> uses snippets as we already have more than the mvpg one in the queue.
> 
> So I'm having Steffen looking into a solution for this problem. My first
> idea was to bring the used snippets into the unittests.cfg but I
> disliked that we then would have compile instructions in another file.
> Maybe there's a way to include that into the makefile in a clever way?

I haven't tried, but maybe you could replace the $(snippets) in the last 
line with

  $(wildcard snippets/$@.gbin)

or something similar?

  Thomas