tools/bootconfig: Align the bootconfig applied initrd

Hi,

This is the 5th version of the bootconfig tool update to align the total size of initrd + bootconfig to 4.

Previous version is here;

https://lkml.kernel.org/r/160571371674.277955.11736890010190945946.stgit@devnote2

This version fixes bugs in [2/4] and [3/4] and cleans up code in [3/4].

To adjust the file size, the bootconfig tool adds padding null characters in between the boot configuration data and the footer.

The changing points are
- The bootconfig applied initrd image size is aligned to 4.
- To insert the padding null ('\0') bytes, the size in the footer can be bigger than the actual bootconfig file size.
- But the max size of the boot configuration file is same, because the max size doesn't include the last null characters.

In this series I keep 4 bytes aligned instead of longer size, because only I could found was that the grub might align the initrd filesize to 4, and U-Boot/EDK2 would not change it. So I couldn't say what is the best size.

Anyway, I updated the documentation too, which clearly says that the above changing points, and if the bootloader pass the wrong size, kernel will not find bootconfig from the initrd.

Thank you,

---

Masami Hiramatsu (4):
tools/bootconfig: Fix errno reference after printf() tools/bootconfig: Fix to check the write failure correctly tools/bootconfig: Align the bootconfig applied initrd image size to 4
docs: bootconfig: Update file format on initrd image

 tools/bootconfig/main.c             |  121 +++++++++++++++++++++++------------
 tools/bootconfig/test-bootconfig.sh |    6 +-
 2 files changed, 85 insertions(+), 42 deletions(-)

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Masami Hiramatsu (Linaro) <[email protected]>