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    SubjectFwd: Can we remove the Zone_DMA?
    Thanks for your reply.And do you means that , If I use a modern PC,such as
    my pc (CPU:Intel dual-core 2.6GHZ; Memory 2GB; And no pci ).I can remove the
    ZONE_DMA .And make sure this system also run smoothly as before?

    在 2010年4月4日 下午1:07,Daniel Hazelton <>写道:

    On Sunday 04 April 2010 12:21:54 am tek-life wrote:
    > > I’m a newbie on the linux kernel. Now I am reading the source code of
    > > Linux . I have a question in the following about ZONE_DMA.
    > >
    > >
    > > In Linux , The Memory is divided to three zone. They are ZONE_DMA
    > > 、ZONE_NORMAL and ZONE_HIGHMEM. From the book of "Undstand the Linux
    > > kernel ", the ZONE_DMA has the effect that the Direct Memory Access
    > > (DMA) processors for old ISA buses have a strong limitation: they are
    > > able to address only the first 16 MB of RAM. SO ,we must set a zone
    > > for the DMA on ISA bus. And I suspect that the hardware has
    > > developed so quickly .And in this days the ISA has been weeded out.
    > > And so ,if we not defined the ZONE_DMA, is the system be effected? And
    > > why not remove ZONE_DMA from the kernel . If it cann‘t to do so,the
    > > compatibility is the only reason?
    > While ISA is gone as a true peripheral interconnect for new systems it
    > does,
    > actually, still live on in a lot of systems that Linux still supports.
    > While
    > those systems, generally, are running the same kernel and userspace they
    > were
    > a decade ago I have no doubt that somebody might find an old machine and
    > put
    > Linux on it - just because they could.
    > And that also discounts the non-IBM PC machines that are out there that
    > Linux
    > also supports. While I don't know enough about them to say for sure, I am
    > quite certain that at least some of them are still using the ISA bus.
    > DRH

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