Messages in this thread | | | Date | Tue, 31 Oct 2006 07:14:09 -0800 | From | Jun Sun <> | Subject | Re: reserve memory in low physical address - possible? |
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On Tue, Oct 31, 2006 at 07:45:57AM -0500, Mark Hounschell wrote: > 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? >
I took a look. The patch will allocate (actually pre-allocate) a big chunk at boot time, which is arguably more friendly to MM subsystem. However, you cannot specify the location of the memory chunk which is what I want.
Thanks.
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