Re: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

From: Bryan O'Donoghue
Date: Thu Jan 08 2015 - 07:11:00 EST


On 07/01/15 23:45, Ong, Boon Leong wrote:
Since BIOS and grub code both use 0x00000000 as the 'off' address I think it
makes sense for the kernel to continue to use that address.

Just add on top of what Daren mentioned in another mail, based on the Quark document,
the base address can start from zero. Say lo=0, hi=0, and WM & RM may be changed from default value,
1st 1KiB will be marked as IMR. It seems to me that there is no good way to test if an IMR is 'occupied' and/or 'enabled'
since enable-bit is not available. But, what is benefit of testing against lo=0 & hi=0? The logic to calculate size will work under
lo=0 & hi=0 anway.

Hi Boon Leong.

I think it does make sense to add a check for rmask and wmask in the 'access all' state when determining if an IMR is enabled on X1000 or not.

My own view is that it's not really desirable and easier to debug IMRs
generally on a platform if overlaps aren't allowed.
I do agree on the benefit listed above. Perhaps, you can add explanation here
to mention the design decision.

Will do.


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