Date: Thu, 31 Jan 2008 23:23:58 +0100 From: Gary Jennejohn <gary.jennejohn@freenet.de> To: Scott Long <scottl@samsco.org> 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: <20080131232358.6cc55327@peedub.jennejohn.org> In-Reply-To: <47A2248D.2050203@samsco.org> References: <20080130104615.717f3ff2@peedub.jennejohn.org> <47A20AA6.2020506@samsco.org> <20080131203636.71b7c4d8@peedub.jennejohn.org> <47A2248D.2050203@samsco.org>
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On Thu, 31 Jan 2008 12:42:05 -0700 Scott Long <scottl@samsco.org> wrote: > Gary Jennejohn wrote: > > 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. > Ah yes, I remember seeing something about the card using 39 bits for addresses. And you're correct, part of the memory was mapped from 0x100000000 to 0x11ffeffff. I was thinking about getting the Adaptec 29320LPE, which is a PCIe x1 card. Think that would have problems with 4GB? That would be the ahd driver, I believe. --- Gary Jennejohn
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