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From: "Jared Hulbert" <jaredeh@gmail.com>
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Subject: Re: [PATCH 00/10] AXFS: Advanced XIP filesystem
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>> How is one expected to read those last 4 bytes of a loopbacked file?
>> Are they unreadable?  We can add the padding.   I am just wondering if
>> this is a bug or a known limitation in the loopback handling or if
>> there is a different safer way of reading block devs with truncated
>> last blocks.
>
> Can't you just include the final magic into the last block, thereby
> making the size a clean multiple of 4k?  It looks as if you have some
> padding before the magic anyway.  So you just have to make sure the
> padding is at least 4 bytes and write the magic to the end of it.  Apart
> from solving this bug, it should also save you some space. ;)

I'm going to have to look into this n*4K thing.  The image doesn't
need to be aligned.  There shouldn't be any last block to put the
magic in.  But I haven't messed with the mkfs.axfs code for a while.