Re: port-vax/49517: si driver has DMA problems

[Anders Magnusson <ragge%ludd.ltu.se@localhost>]

The following reply was made to PR port-vax/49517; it has been noted by GNATS.

From: Anders Magnusson <ragge%ludd.ltu.se@localhost>
To: gnats-bugs%NetBSD.org@localhost, port-vax-maintainer%NetBSD.org@localhost,
        gnats-admin%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost, martin%NetBSD.org@localhost
Cc: 
Subject: Re: port-vax/49517: si driver has DMA problems
Date: Tue, 20 Jan 2015 20:19:54 +0100

 That depends on the hardware.  A VS2K for example have 16k.
 The MV3100 has 128k DMA space.  It is actually a separate block of memory
 (not in normal RAM) from where the data later must be copied to its 
 destination.
 
 David Brownlee skrev den 2015-01-20 17:30:
 > The following reply was made to PR port-vax/49517; it has been noted by GNATS.
 >
 > From: David Brownlee <abs%absd.org@localhost>
 > To: "gnats-bugs%netbsd.org@localhost" <gnats-bugs%netbsd.org@localhost>
 > Cc: port-vax-maintainer%netbsd.org@localhost,
 > 	"gnats-admin%netbsd.org@localhost" <gnats-admin%netbsd.org@localhost>, netbsd-bugs%netbsd.org@localhost,
 > 	port-vax List <port-vax%netbsd.org@localhost>
 > Subject: Re: port-vax/49517: si driver has DMA problems
 > Date: Tue, 20 Jan 2015 16:28:05 +0000
 >
 >   Just a random thought, could this is be related to trying a MAXPHYS
 >   (64K) sized transfer? I seem to recall something related to the vax
 >   NCR5380 having a less than 64K max transfer size limit...
 >   
 >   On 30 December 2014 at 21:10,  <martin%netbsd.org@localhost> wrote:
 >   >>Number:         49517
 >   >>Category:       port-vax
 >   >>Synopsis:       si driver has DMA problems
 >   >>Confidential:   no
 >   >>Severity:       serious
 >   >>Priority:       medium
 >   >>Responsible:    port-vax-maintainer
 >   >>State:          open
 >   >>Class:          sw-bug
 >   >>Submitter-Id:   net
 >   >>Arrival-Date:   Tue Dec 30 21:10:00 +0000 2014
 >   >>Originator:     Martin Husemann
 >   >>Release:        NetBSD 7.99.2
 >   >>Organization:
 >   > The NetBSD Foundation, Inc.
 >   >>Environment:
 >   > System: NetBSD  7.99.3 NetBSD 7.99.3 (GENERIC) #8: Tue Dec 30 19:18:41 CET 2014  martin%seven-days-to-the-wolves.aprisoft.de@localhost:/usr/obj/vax/usr/src/sys/arch/vax/compile/GENERIC vax
 >   > Architecture: vax
 >   > Machine: vax
 >   >>Description:
 >   >
 >   > The NCR5380 driver seems to corrupt kernel memory on incoming (i.e. read)
 >   > transfers basically imediately. Random things happen (programs die, ...)
 >   > after a few transfers.
 >   >
 >   > Forcing all IN operations to do PIO makes the system pretty much stable:
 >   >
 >   > Index: ncr.c
 >   > ===================================================================
 >   > RCS file: /cvsroot/src/sys/arch/vax/vsa/ncr.c,v
 >   > retrieving revision 1.48
 >   > diff -u -r1.48 ncr.c
 >   > --- ncr.c       14 Dec 2010 23:31:16 -0000      1.48
 >   > +++ ncr.c       30 Dec 2014 21:01:29 -0000
 >   > @@ -254,6 +254,9 @@
 >   >         if (sr->sr_flags & SR_IMMED)
 >   >                 return;
 >   >
 >   > +       if (!(xs->xs_control & XS_CTL_DATA_OUT))
 >   > +               return;
 >   > +
 >   >         xlen = ncr_sc->sc_datalen;
 >   >
 >   >         /* Make sure our caller checked sc_min_dma_len. */
 >   >
 >   >
 >   >>How-To-Repeat:
 >   >
 >   > Try to install on a MicroVax 3100 to a scsi disk.
 >   >
 >   >>Fix:
 >   > n/a
 >   >
 >