Date: Wed, 18 Jun 2003 03:00:00 +0200 From: Bernd Walter <ticso@cicely12.cicely.de> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-alpha@freebsd.org Subject: Re: 5.1beta2 on Alpha ES40 w/ 32GB pys ram Message-ID: <20030618005958.GD3626@cicely12.cicely.de> In-Reply-To: <16110.27799.68056.48679@grasshopper.cs.duke.edu> References: <16094.16676.273466.121560@grasshopper.cs.duke.edu> <20030613190624.W36168-100000@mail.chesapeake.net> <16110.27799.68056.48679@grasshopper.cs.duke.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Jun 16, 2003 at 09:19:19PM -0400, Andrew Gallatin wrote: > > Jeff Roberson writes: > > On Wed, 4 Jun 2003, Andrew Gallatin wrote: > > > > > > > > > > > Andrea Cocito writes: > > > > Hallo, > > > > > > > > I have a little (??) problem trying to boot FreeBSD 5.1beta2 > > > > on an ES40 with 32 gigs of physical RAM, this is the status: > > > > > > > > > > You have to limit physical memory to 2GB or less. Otherwise, DMAs > > > won't work. > > > > > > Drew > > > > Is this because we dont program the TLB on the DMA controller? I heard > > rumors that sparc64 has code to handle all of this for their chipsets. If > > they have the infrastructure it may not be hard to port. > > > > We program it, but we do not take full advantage of it: > > Most alphas have 4 DMA windows. We typically use 1 window for ISA Do you have an overview of which ones don't have 4 windows? Is the direct map sufficient for them or can we increase the ISA map size in such a case? > dma, meaning we can do zero-copy (no bounce buffer) DMA to any ISA > device. This is only 16MB in size. > > We use another window as a 'direct map' window, meaning we map > physical addresses 0..1GB (or 0..2GB) into PCI address space, > generally at offset 1GB in PCI address space. What are the reasons for this difference? Is it just because of SRM interaction or some chipset limitation? > We should use another window for 32-bit PCI DMA, and we should enable > the "monster window" bit, so that devices which are DAC (64-bit) > address capable don't need to deal with the TLB on the DMA > controller. We don't currently do either. In the first step I would say we should start checking cards for DAC support and if there are enough of them then do the monster window thing first. I asume it's not that critical for >2G machine owners to replace non DAC cards, especially as I believe many non DAC cards have currently non busdma drivers as well. The S/G map can be done later if still required. Maybe with a tuneable size as a 4G map takes 4M map - checked for 21172. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030618005958.GD3626>