Re: [LinuxBIOS] [Fwd: Hardware Write-Protect for BIOS & EC]

[Lu, Yinghai]

1. in you suggestion. When you are flash the rom, if sth go wrong (lose
power), you will corrupt your rom.
2. are you going to use fallback image with normal image?
If so you can disable the write to last 128K ( fallback image part) via
HW jumper.  ---- No one could change the fallback image without remove
the jumper. Some MB already have that for last 64k.

YH

-----Original Message-----
From: [e-mail]
[mailto:[e-mail]] On Behalf Of Jim Gettys
Sent: Thursday, March 23, 2006 7:26 AM
To: LinuxBIOS
Subject: [LinuxBIOS] [Fwd: Hardware Write-Protect for BIOS & EC]

OK, here's the proposed solution for write protect of the OLPC BIOS.

Short of phishing attacks, I think it should suffice; but I'd like
people here to shoot at the scheme in case I'm missing something.
                          Regards,
                              - Jim

[LinuxBIOS] [Fwd: Hardware Write-Protect for BIOS & EC]

[Ronald G Minnich]

Lu, Yinghai wrote:
> in you suggestion. When you are flash the rom, if sth go wrong (lose
>
> power), you will corrupt your rom.
> 2. are you going to use fallback image with normal image?
> If so you can disable the write to last 128K ( fallback image part) via
> HW jumper.  ---- No one could change the fallback image without remove
> the jumper. Some MB already have that for last 64k.

I think that having a 'you can never write this' bios image would be 
useful. The power fail scenario is a concern.

ron

[LinuxBIOS] [Fwd: Hardware Write-Protect for BIOS & EC]

[Richard Smith]

> I think that having a 'you can never write this' bios image would be
> useful. The power fail scenario is a concern.

Many flash parts support a hardware lock where you can set a split. 
Areas that have been hardware locked can only be reprogrammed via the
right programming voltage which is normally much higher than Vcc.

[LinuxBIOS] [Fwd: Hardware Write-Protect for BIOS & EC]

[Bari Ari]

Picking a flash device with a boot block that cannot be rewritten just 
via any possible software routine alone and only by being combined with 
hardware intervention will work.

The parts that require a higher programming voltage that Richard 
mentions is one good possible way.

This would also recover a damaged BIOS attacked by even phishers.

If the flash update was somehow corrupted via power interruption, 
infected BIOS update with a good checksum, etc. the boot section would 
still have an good booter.

-Bari

Richard Smith wrote:
> > I think that having a 'you can never write this' bios image would be
> > useful. The power fail scenario is a concern.
>
> Many flash parts support a hardware lock where you can set a split. 
> Areas that have been hardware locked can only be reprogrammed via the
> right programming voltage which is normally much higher than Vcc.