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

[Thomas Huth <thuth@redhat.com>]

On 21/06/2021 14.39, Janosch Frank wrote:
> On 6/21/21 2:32 PM, Thomas Huth wrote:
>> 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?
> 
> That starts falling apart when multiple tests use the same snippet, no?

That's true ... Maybe something like:

  $(filter %.gbin,$^)

?

  Thomas