Date: Thu, 31 Jan 2008 12:42:05 -0700 From: Scott Long <scottl@samsco.org> To: gary.jennejohn@freenet.de Cc: freebsd-scsi@freebsd.org Subject: Re: data corruption with ahc driver and 4GB of memory using a FBSD-8 64-bit installation? Message-ID: <47A2248D.2050203@samsco.org> In-Reply-To: <20080131203636.71b7c4d8@peedub.jennejohn.org> References: <20080130104615.717f3ff2@peedub.jennejohn.org> <47A20AA6.2020506@samsco.org> <20080131203636.71b7c4d8@peedub.jennejohn.org>
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Gary Jennejohn wrote: > On Thu, 31 Jan 2008 10:51:34 -0700 > Scott Long <scottl@samsco.org> wrote: > >> Gary Jennejohn wrote: >>> I think $(subject) says it all. >>> >>> I have a Gigabyte AM2 mobo with an AMD64 X2 CPU installed. >>> >>> The SCIS set up looks lie this: >>> >>> 29160N <--> da0 <--> da1 >>> >>> da0 has a 32-bit installation of FBSD-8 >>> da1 has a 64-bit installtion of FBSD-8 >>> >>> If I install 4GB of memory (4 DIMMs) in the system I see the following >>> behavior: >>> >>> a) booting from da0 works just fine and I can access both disks without >>> any problem. >>> >>> b) booting from da1 results in (apparent) data errors such that /bin/sh >>> dies with SIGILL and /rescue/sh dies with SIGSEGV. >>> >>> c) trying to do an installation of a snapshot of FBSD-8 to a SCSI disk >>> results in various problems, among others a kernel panic in ffs_balloc >>> during newfs. >>> >>> d) an installation to a SATA disk succeeds and the system runs just >>> fine. >>> >>> With only 3GB of memory everything works. Of course, I'd really like to >>> be able to use the entire 4GB. And I want to keep my SCSI disks. >>> >>> I suspect that ahc has some sort of problem in 64-bit mode. However, >>> I'm not certain whether the 32-bit installation works with 4GB simply >>> because the ahc driver uses bounce buffers. >>> >>> Has anybody else seen this? Can anyone confirm that ahc does indeed >>> have an error with 4GB and a 64-bit installation? >>> >>> BTW please put me in the Cc because I'm not subscribed to this ML. >>> >> The ahc driver should work with >4GB, and in fact that was a standard >> part of the test suite back when it was still in active development. If >> it doesn't work now then it's due to some sort of bitrot. I can try to >> test and debug it myself, but I'm pretty overcommitted so I can't >> guarantee that I'll get to it. If others would like to help test and >> debug, I'm happy to answer questions and provide assistance. >> > > Well, the thing which I find confusing is that the 32-bit installation > works without any problems. I would expect the 64-bit installation to > work with 4GB, if anything does. > > Does the 32-bit version use bounce buffers? > > I'll try poking around some, but the 64-bit install is my (money earning) > work station and I can't afford to trash it, so I'm sort of unwilling to > risk it. And I don't have any spare SCSI disks to use for testing. Well, > I suppose I could sacrifice the 32-bit disk. It's not so important. > > Any hints on where to start looking? > Even with only 4GB of physical RAM, the motherboard will remap part of that RAM to be above the 4GB barrier. So running in 64-bit mode with only 4GB of RAM will still exercise the >4GB bugs. Let me think on where to point you for debugging... The ahc cards don't normally use bounce buffers; they are designed to handle up to 2^39 bytes of RAM directly. Scott
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