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, Luigi 'Comio' Mantellini wrote:
- The mkimage calculate hashes before that timestamp is added to
image. is it better exchange the order of these operations (before add timestamp then calculate hashes)?
Please see below.
- Does the new format assure that the complete image (_all_ sections,
images, ramdisks, configurations, blobs) are covered by at least an hash value?
Currently, the hash calculation is performed only over binary data of component images (kernel, ramdisk, fdt, etc). In particular, timestamp information is not protected by the hash, so the ordering of hash calculation and timestamp addition doesn't matter.
Ok. I agree
should mkimage add at least a hash value for the root node?
Adding a hash value for the root node only will not be easy. An easier approach I think would be to add a hash value for the entire FIT image.
Ok.
In addition to the previous question:
- 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 filename285875 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).
Best regards.
luigi
HTH, Bartlomiej