From mboxrd@z Thu Jan  1 00:00:00 1970
From: Reinhard Meyer <u-boot@emk-elektronik.de>
Date: Mon, 31 Jan 2011 08:17:36 +0100
Subject: [U-Boot] SPI flash protection
In-Reply-To: <4D465C4B.3020201@free.fr>
References: <20110129170048.GE20942@kw.sim.vm.gnt>
	<4D453111.50107@free.fr>	<20110130145610.GA20073@kw.sim.vm.gnt>
	<4D459D98.6000704@free.fr>	<20110131003120.GC20073@kw.sim.vm.gnt>
	<4D465C4B.3020201@free.fr>
Message-ID: <4D466210.7090906@emk-elektronik.de>
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To: u-boot@lists.denx.de

Dear Albert ARIBAUD, Simon Guinot,
>
>>>> Here is the protect area map for a MX25L4005A 4Mb flash:
>>>>
>>>>     bit  2 1 0 | protect level
>>>>    ____________|_______________
>>>>          0 0 0 | none
>>>>          0 0 1 | block 7
>>>>          0 1 0 | block 6-7
>>>>          0 1 1 | block 4-7
>>>>          1 * * | all
>> Block size is 64KB. The compiled U-Boot image is about 220KB and
>> environment is 4KB. So, 4 blocks are required for U-Boot.

I don't know your particular hardware, but is not u-boot (or the
initial bootloader if there is any) fetched from the *beginning*
of the flash?

If so, you would have to *hardware* protect the *entire* flash.

In this case, a *software* protection mechanism like for NOR flash
would be a better choice.

Best Regards,
Reinhard