Fwd: Can we remove the Zone_DMA?
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From: tek-life on 4 Apr 2010 01:40 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? �� 2010��4��4�� ����1:07��Daniel Hazelton <dhazelton(a)enter.net>��� 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 > -- Laboratory of Service Computing Technology and System p-web:http://tek-life.org/blog QQ:150439216 -- Laboratory of Service Computing Technology and System p-web:http://tek-life.org/blog QQ:150439216 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Daniel Hazelton on 4 Apr 2010 03:50 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. DRH > �� 2010��4��4�� ����1:07��Daniel Hazelton <dhazelton(a)enter.net>��� > > 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(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Thomas Fjellstrom on 4 Apr 2010 05:10
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 > > > �� 2010��4��4�� ����1:07��Daniel Hazelton <dhazelton(a)enter.net>��� > > > > 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(a)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(a)strangesoft.net -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |