Hi Reinhard,
On Mon, Jan 31, 2011 at 08:17:36AM +0100, Reinhard Meyer wrote:
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.
Yes you are right. Moreover the protected blocks (for a same register value) _could_ be different on an another Macronix device. For example, larger flash use 4 bits instead of 3 for block protection.
In this case, a *software* protection mechanism like for NOR flash would be a better choice.
Or no protection at all. After all, there is no such mechanism implemented for u-boot and Linux...
Best regards,
Simon