[U-Boot-Users] New Image format: headers hashes.

[Bartlomiej Sieka <tur@semihalf.com>]

Luigi 'Comio' Mantellini wrote:
> Hi Bartlomiej,
> 
> thank you for the answers. See my comments below.
> 
> On gio, 2008-04-03 at 11:31 +0200, Bartlomiej Sieka wrote:
>> Hi Luigi,
>>
>> You wrote:
>>> On gio, 2008-03-27 at 12:13 +0100, L
>>> - I'm interested to calculate and store from U-boot code but the 
>>> fit_image_set_hashes is compiled only when the USE_HOSTCC symbol is 
>>> defined. Why? Is there a particular reason?
>> There's no need for the function that you mention in current U-Boot
>> code, that's the reason why it's under USE_HOSTCC. If you're planning on
>> adding code to U-Boot that will use fit_image_set_hashes(), then just
>> remove the USE_HOSTCC #define's from around this function.
>>
>>
>>  > I think that a lot of
>>  > useful functions (ifdef-ed by USE_HOSTCC) should be available also in
>>  > u-boot code, anyway the linker will drop the unused functions.
>>
>> I don't think the linker will do this in case of U-Boot:
>>
>> With the following patch:
>>
>> diff --git a/common/image.c b/common/image.c
>> index f04826a..850a9e4 100644
>> --- a/common/image.c
>> +++ b/common/image.c
>> @@ -1950,7 +1950,6 @@ static int calculate_hash (const void *data, int 
>> data_len,
>>   	return 0;
>>   }
>>
>> -#ifdef USE_HOSTCC
>>   /**
>>    * fit_set_hashes - process FIT component image nodes and calculate hashes
>>    * @fit: pointer to the FIT format image header
>> @@ -2119,7 +2118,6 @@ int fit_image_hash_set_value (void *fit, int 
>> noffset, uint
>>
>>   	return 0;
>>   }
>> -#endif /* USE_HOSTCC */
>>
>>   /**
>>    * fit_image_check_hashes - verify data intergity
>>
>>
>> I see:
>>
>> $ ${CROSS_COMPILE}nm -S common/image.o | grep fit_image_set_hashes
>> 0000155c 000001f4 T fit_image_set_hashes
>> $ ${CROSS_COMPILE}nm -S common/libcommon.a | grep fit_image_set_hashes
>> 0000155c 000001f4 T fit_image_set_hashes
>> $ ${CROSS_COMPILE}nm -S u-boot | grep fit_image_set_hashes
>> fffb1924 000001f4 T fit_image_set_hashes
>>
>>
>> There's also size increase with the patch applied:
>>     text    data     bss     dec     hex filename
>>   284615   15556  357120  657291   a078b ./u-boot
>>
>>     text    data     bss     dec     hex filename
>>   285875   15572  357120  658567   a0c87 u-boot
>>
>>
> 
> Before to make this test, you should strip the elf-file in order to omit
> the non-used code. Alternatively you should check the size of the
> u-boot.bin file (that is striped by definition).

"objcopy -O binary" which is used to create u-boot.bin from u-boot
doesn't remove unused functions -- code for fit_image_set_hashes (and
other functions removed from under #ifdef USE_HOSTCC by the patch) is
present in u-boot.bin.

If you add enough of such dead code, you'll see the increase in size of 
u-boot.bin, or run into linking problems -- depending on the particular 
linker script used for the target.

Regards,
Bartlomiej