Re: Removal of GEOM_BSD, GEOM_MBR, GEOM_PC98 and GEOM_SUNLABEL

From: Christoph Mallon <christoph.mallon_at_gmx.de>
Date: Sat, 04 Apr 2009 14:27:57 +0200
Wilkinson, Alex schrieb:
>     0n Thu, Apr 02, 2009 at 09:44:02PM -0700, Marcel Moolenaar wrote: 
> 
>     >*snip*
>     >> 000001b0  00 00 00 00 00 f2 0e 00  00 00 00 00 00 00 00 01   
>     >> |................|
>     >> 000001c0  c1 ff 83 ef ff ff 3f 00  00 00 21 17 00 01 00 00   
>     >> |......?...!.....|
>     >> 000001d0  c1 ff 05 ef ff ff 60 17  00 01 b0 a8 fe 02 00 00   
>     >> |......`.........|
>     >> 000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   
>     >> |................|
>     >> 000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa   
>     >> |..............U.|
>     >*snip*
>     >
>     >It looks like you have a boot menu entry at 0x1b6. Can you
>     >try the following patch:
> 
> OK, excuse my lack of skill here, but Marcel how in the hell did you decifer that ?

Read from the back: The last two bytes (55 AA) are a magic marker. 
Before that are four times 16 bytes, which describe the four possible 
partitions (start, size, type etc.). For MBRs (Master Boot Record) all 
four can be used, for EBRs (Extended Boot Record) the 3rd and 4th are 
always zero (i.e. unused). Before that (0x01B5 till 0x01BD) are are the 
nine non-zero bytes, which caused the trouble.

More info about the layout of the partition entries etc.:
http://en.wikipedia.org/wiki/Extended_Boot_Record

	Christoph
Received on Sat Apr 04 2009 - 10:54:42 UTC

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