[klibc] bunch of small fixes

H. Peter Anvin hpa at zytor.com
Fri Mar 28 15:54:09 PDT 2008

Nigel Cunningham wrote:
> Hi.
> On Fri, 2008-03-28 at 21:32 +0100, maximilian attems wrote:
>> hello hpa,
>> updated/rebased my klibc merge branch.
>> David critized the toxonice fstype support due to the
>> missing real MAGIC of tuxonice. I agree that "z" and "Z"
>> leaves too much room for misrecognition thus patch dropped.
>> added a quick utils cleanup and a mknod switch.
> Thanks for cc'ing me. The reason it is just a 'z' or 'Z' is that it
> hasn't changed since the days when we had to fit major & minor numbers,
> a block and the block size. (There simply wasn't room for anything more
> than one character). Since you've raised the issue, I've had another
> look. The format is currently:
> Byte 0:     z/Z: Original swapspace type.
>      1-4:   dev_t for first block of header
>      5:     blocksize - top bit = whether previously attempted to resume
>      6-9:   index of first block of header
> The dev_t is necessary because (unlike [u]swsusp), we support using
> multiple swap devices for storing the image, so the header might start
> on a different partition to the swapspace signature.
> Clearly there are some unused bits in there now. How about if I
> rearranged things:
> Bytes 0-1:   Signature ascii tx with the high bit on in
>              Byte 0 if the original signature was SWAPSPACE2.
>              Byte 1 if we tried to resume before.
>       2-5:   dev_t for first block  of header
>       6-9:   index for first block of header
> Would that help address the potential misrecognition issue?

Well, two bytes is better than one (and non-ASCII is better than ASCII), 
but it's still anemic.  I'm recommending that people use 64-bit magics 
these days.


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