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[caster420]

It is disabling you from using a lower kernel than 4552.  I dont think it is physically 'blowing' an efuse but rather changing a value of the efuse.  From what i have read and what i understand of what i have read, is that your xbox encrypts things using a per-box key, which is based on an algorithm and fuseset values.  So, if you changed the value of a fuse, your per-box key would change.  This would prevent your older encrypted flash from being valid with your system.  

If you look at a boot log of the recent Xell boot loader, you see several fuse values.  These vary from 360 to 360, which is why when you swap CPU's or NAND's (tsop's), they do not work on another system.  By removing R6T3, you disabling the eFuse power source which changes the value of it.  Hence, even though you may upgrade to 4552, you can downgrade to an earlier kernel assuming you have taken the appropriate measures (dumping the NAND before upgrading).

That is my take on it anyways.  I may be off base but this is how i have interpreted posts of those who know a hell of a lot more than me on the subject.

Caster.

[BNary]

QUOTE(caster420 @ Mar 29 2007, 05:14 PM)

It is disabling you from using a lower kernel than 4552.  I dont think it is physically 'blowing' an efuse but rather changing a value of the efuse.  From what i have read and what i understand of what i have read, is that your xbox encrypts things using a per-box key, which is based on an algorithm and fuseset values.  So, if you changed the value of a fuse, your per-box key would change.  This would prevent your older encrypted flash from being valid with your system.  

If you look at a boot log of the recent Xell boot loader, you see several fuse values.  These vary from 360 to 360, which is why when you swap CPU's or NAND's (tsop's), they do not work on another system.  By removing R6T3, you disabling the eFuse power source which changes the value of it.  Hence, even though you may upgrade to 4552, you can downgrade to an earlier kernel assuming you have taken the appropriate measures (dumping the NAND before upgrading).

That is my take on it anyways.  I may be off base but this is how i have interpreted posts of those who know a hell of a lot more than me on the subject.

Caster.

Ok, so if we find an exploit for 4552, we can downgrade it to earlier kernels... right?

[skorchir]

If you find an exploit in 4552 there will be no need to downgrade

[BNary]

QUOTE(skorchir @ Mar 29 2007, 06:39 PM)

If you find an exploit in 4552 there will be no need to downgrade

Of course.. but I meant an exploit for downgrading, like the PSP's scene.
My mainly question was is the eFuse blowing a hardware-level process, so downgrading is impossible at all.