From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jes Sorensen Date: Tue, 15 Feb 2000 21:03:03 +0000 Subject: Re: [Linux-ia64] LINUX IA64 Memory Support Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> "Venkatesh" = Venkatesh Ramamurthy writes: Venkatesh> Hi, Is there any way in which one can allocate memory say Venkatesh> below 4 GB ( physical address )in drivers. TIA Venkatesh This is not IA64 specific actually, so consider it a general answer rather than an IA64 one. A regular GFP_KERNEL should give you memory within the PCI DMA'able area, which with the old PCI system meant within the 4GB range. GFP_DMA will give you something within the ISA DMA space. However, in principle none of the above means that the memory is within the lower 4GB memory range, if the machine in question has an IOMMU type device, you may be handed memory which is in the middle of the memory space, but which is mapped to the 4GB the PCI bus in the machine can see. With the new PCI allocation system it is even more flexible, here you may get addresess anywhere and you then tell the PCI subsystem at run time to map the memory to the space the PCI bus can address. This means it will be possible to support systems with for instance 200 PCI busses (if someone feels like building such) etc. Jes