How to read/write SPI flash descriptor

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Hello all,

I used chipsec to evaluate my hardware.

And I got following report:

[-] Software has write access to SPI flash descriptor
[-] FAILED: SPI flash permissions allow SW to write flash descriptor

I look at the chipsec source code and find that this is read from frap
register(SPIBAR + 50h).
However I can't find the spec how to read the SPI flash descriptor itself.
I find some code from flashrom:
https://github.com/flashrom/flashrom/blob/db7482bb72035fab8386226d1720cde09=
e0c700e/ich_descriptors.c

It reads SPI flash descriptor using MMIO, but also I don't know how to
write it.(it has no effect when write to the same register with read).

Any hints?

Thanks,
Li Qiang

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