Re: I did a test on a DEC AlphaStation 600 and the SCSI driver seems borked

[Jason Thorpe <thorpej%me.com@localhost>]

> On Feb 17, 2026, at 3:58 AM, Magnus Lindholm <linmag7%gmail.com@localhost> wrote:
> 
> I've been struggling with the ISP driver on Linux for a while,
> (qla1280 as linux call it). The Linux driver
> can be built as a "64-bit driver" by setting  QLA_64BIT_PTR which is
> by default if we have
> CONFIG_ARCH_DMA_ADDR_T_64BIT. This is actually required for the driver
> to work on some SGI/mips
> systems. My issues with the driver turned out to be DAC support on
> Alpha. The driver ran fine in 64-bit mode
> with a 64-bit DMA_MASK enbeling the "monster window" on Alpha. This
> worked fine on Rawhide based
> Alphas such as the Alphaserver 4100, but does not work on tsunami
> based Alphas, such as ES40.

Interesting.

> At least when there is more than 2GB RAM available, if enabled, the
> "monster window" is activated
> on Alpha systems with more than 2GB RAM if the DMA_MASK is > 40 bits.
> Anyways I ended up with
> the conclusion that the Linux driver was fine, but there was issues
> with PCI/DAC/DMA on certain Alphas

Hm, I added support for the monster window to NetBSD/alpha in:

$NetBSD: tsp_dma.c,v 1.17 2021/05/27 22:11:31 thorpej Exp $

(Only for Tsunami, etc. systems)

> 32-bit mode on the ISP driver worked on all combinations of ISP cards
> (tested ISP1080, ISP1040revB and
> ISP1040revC, ISP1020). When the driver was in 64-bit mode with full
> 64-bit DMA mask, certain combination
> of cards and Alpha chipsets and installed RAM did not work, most
> notably any ISP card with a 32-bit PCI
> interface did not work on tsunami based Alphas that had more than 2GB
> ram installed. At the time I was
> working on this issue for Linux I looked at how NetBSD did things for
> the card since my qlogic ISP1040 card
> worked fine on NetBSD, but maybe NetBSD never activated the monster
> window for DMA transfers?

Depends on when you looked; see above :-)

> Anyway, this was maybe a bit off topic but I wanted to share some of
> my experiences with qlogic ISP cards
> on Alpha, even though it's mostly on Linux.

This suggests to me that I should probably change the tsp_dma code, then, to enable and advertise the monster direct-mapped window only on systems that actually could benefit from it (i.e. systems with > 2GB RAM).

-- thorpej