Re: [kvm-unit-tests PATCH v2 14/16] arm/run: Allow Migration tests

[Auger Eric <eric.auger@redhat.com>]

Hi Drew,
On 1/13/20 7:40 PM, Andrew Jones wrote:
> On Fri, Jan 10, 2020 at 03:54:10PM +0100, Eric Auger wrote:
>> Let's link getchar.o to use puts and getchar from the
>> tests.
>>
>> Then allow tests belonging to the migration group to
>> trigger the migration from the test code by putting
>> "migrate" into the uart. Then the code can wait for the
>> migration completion by using getchar().
>>
>> The __getchar implement is minimalist as it just reads the
>> data register. It is just meant to read the single character
>> emitted at the end of the migration by the runner script.
>>
>> It is not meant to read more data (FIFOs are not enabled).
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> Reviewed-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  arm/Makefile.common |  2 +-
>>  arm/run             |  2 +-
>>  lib/arm/io.c        | 13 +++++++++++++
>>  3 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/arm/Makefile.common b/arm/Makefile.common
>> index 7cc0f04..327f112 100644
>> --- a/arm/Makefile.common
>> +++ b/arm/Makefile.common
>> @@ -32,7 +32,7 @@ CFLAGS += -I $(SRCDIR)/lib -I $(SRCDIR)/lib/libfdt -I lib
>>  asm-offsets = lib/$(ARCH)/asm-offsets.h
>>  include $(SRCDIR)/scripts/asm-offsets.mak
>>  
>> -cflatobjs += lib/util.o
>> +cflatobjs += lib/util.o lib/getchar.o
>>  cflatobjs += lib/alloc_phys.o
>>  cflatobjs += lib/alloc_page.o
>>  cflatobjs += lib/vmalloc.o
>> diff --git a/arm/run b/arm/run
>> index 277db9b..a390ca5 100755
>> --- a/arm/run
>> +++ b/arm/run
>> @@ -61,6 +61,6 @@ fi
>>  M+=",accel=$ACCEL"
>>  command="$qemu -nodefaults $M -cpu $processor $chr_testdev $pci_testdev"
>>  command+=" -display none -serial stdio -kernel"
>> -command="$(timeout_cmd) $command"
>> +command="$(migration_cmd) $(timeout_cmd) $command"
>>  
>>  run_qemu $command "$@"
>> diff --git a/lib/arm/io.c b/lib/arm/io.c
>> index 99fd315..ed89e19 100644
>> --- a/lib/arm/io.c
>> +++ b/lib/arm/io.c
>> @@ -87,6 +87,19 @@ void puts(const char *s)
>>  	spin_unlock(&uart_lock);
>>  }
>>  
>> +/*
>> + * Minimalist implementation for migration completion detection.
>> + * Needs to be improved for more advanced Rx cases
> 
> Please add that QEMU supports reading a maximum of 16 characters in
> this minimal mode. We could even add a counter and then assert if
> we try to read 16 or more.
> 
>> + */
>> +int __getchar(void)
>> +{
>> +	int ret;
>> +
>> +	ret = readb(uart0_base);
>> +	if (!ret)
>> +		return -1;
>> +	return ret;
>> +}
> 
> What about taking the lock?
> 
>>  
>>  /*
>>   * Defining halt to take 'code' as an argument guarantees that it will
>> -- 
>> 2.20.1
>>
> 
> What do you think of the __getchar below?
> 
> Thanks,
> drew
> 
> 
> diff --git a/lib/arm/io.c b/lib/arm/io.c
> index 99fd31560084..77beb331d6b2 100644
> --- a/lib/arm/io.c
> +++ b/lib/arm/io.c
> @@ -79,6 +79,31 @@ void io_init(void)
>  	chr_testdev_init();
>  }
>  
> +static int ____getchar(void)
> +{
> +	int c;
> +
> +	spin_lock(&uart_lock);
> +	c = readb(uart0_base);
> +	spin_unlock(&uart_lock);
> +
> +	return c ?: -1;
> +}
> +
> +int __getchar(void)
> +{
> +	static int count;
> +	int c;
> +
> +	if ((c = ____getchar()) != -1)
> +		++count;
> +
> +	/* Without special UART initialization we can only read 16 characters. */
> +	assert(count < 16);
> +
> +	return c;
> +}
> +
>  void puts(const char *s)
>  {
>  	spin_lock(&uart_lock);
> 
Yep, I will take your improved version.

Thanks

Eric