Messages in this thread | | | From | Thomas Fjellstrom <> | Subject | Re: Fwd: Can we remove the Zone_DMA? | Date | Sun, 4 Apr 2010 02:16:19 -0600 |
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On April 4, 2010, Daniel Hazelton wrote: > On Sunday 04 April 2010 01:33:09 am tek-life wrote: > > 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? > > *MAYBE* - if you don't use parallel ports, floppy drives or similar. > There actually are still a lot of devices that use the ISA bus in a > modern PC - even the keyboard (well, not USB ones) is an ISA device. > > Simple fact is that if it was possible to configure it out and not cause > massive problems somebody would have already spun out a patch to allow > just that.
Some onboard motherboard devices may also be ISA devices.
> DRH > > > 在 2010年4月4日 下午1:07,Daniel Hazelton <dhazelton@enter.net>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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" > in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- Thomas Fjellstrom tfjellstrom@strangesoft.net -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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