Re: reserve memory in low physical address - possible?

Mark Hounschell
2006-10-31T12:46:00Z

Jun Sun wrote:
> This question is specific to i386 architecture. While I am fairly
> comfortable with Linux kernel, I am not familiar with i386 arch.
>
> My objective is to reserve, or hide from kernel, some memory space in low
> physical address range starting from 0. The memory amount is in the order
> of 100MB to 200MB. The total memory is assumed to be around 512MB.
>
> Is this possible?
>
> I understand it is possible to reserve some memory at the end by
> specifying "mem=xxxM" option in kernel command line. I looked into
> "memmap=xxxM" option but it appears not helpful for what I want.
>
> While searching on the web I also found things like DMA zone and loaders
> etc that all seem to assume the existence low-addressed physical
> memory. True?
>
> I can certainly workaround the loader issue. I can also re-code the real-mode
> part of kernel code to migrate to higher addresses. The DMA zone might be
> a thorny one. Any clues? Are modern PCs still subject to
> the 16MB DMA zone restriction?
>
> Am I too far off from what I want to do?
>
> Thanks.
>
> Jun

Maybe the bigphysarea patch is what you want?

Mark