sparc64/165025: [PATCH] zfsboot support for sparc64

Marius Strobl marius at
Sun Apr 29 16:30:15 UTC 2012

The following reply was made to PR sparc64/165025; it has been noted by GNATS.

From: Marius Strobl <marius at>
To: bug-followup at, at
Subject: Re: sparc64/165025: [PATCH] zfsboot support for sparc64
Date: Sun, 29 Apr 2012 18:10:19 +0200

 On Sun, Apr 22, 2012 at 08:40:13PM +0000, Marius Strobl wrote:
 > The following reply was made to PR sparc64/165025; it has been noted by GNATS.
 > From: Marius Strobl <marius at>
 > To: Gavin Mu < at>
 > Cc: bug-followup at, Kurt Lidl <lidl at>
 > Subject: Re: sparc64/165025: [PATCH] zfsboot support for sparc64
 > Date: Sun, 22 Apr 2012 22:32:11 +0200
 >  On Thu, Apr 12, 2012 at 10:27:31PM +0800, Gavin Mu wrote:
 >  > On Mon, Mar 5, 2012 at 2:06 AM, Marius Strobl <marius at> wrote:
 >  > > Typically, opening and closing devices via OFW causes quite a delay,
 >  > > the exact impact depends on the firmware version and the devices
 >  > > involved though. Therefore, it would be advisable to keep using the
 >  > > current approach of caching opened packages. In what way does this
 >  > > fail with ZFS?
 >  > The error message on Fire V100 is: Fast Data Access MMU Miss
 >  > 
 >  > > Basically, IEEE 1275 just says that support for
 >  > > opening a package more than once depends on the particular package
 >  > > but nothing about concurrently opening different packages. Not
 >  > > being able to concurrently open different packages also doesn't
 >  > > make all that much of a sense as opening one package also means
 >  > > to subsequentially open all the parents up to the root if not
 >  > > already opened and I think to actually have tested opening disks
 >  > > concurrently when writing the current code. Could this fail due
 >  > > to one device actually being opened twice, once via the full path
 >  > > and once via its alias?
 >  > There is no such scene though the code lacks the checking for full
 >  > path/devalias.
 >  > I have tried many times to find the root cause but I think it is
 >  > difficult without open firmware knowledge.
 >  > currently I found that following scenes will cause this issue with my test code:
 >  > 1. do OF_seek(ihandle_t a) just after OF_close(ihandle_t b). in real
 >  > world, OF_seek(a) is the step to read ZFS data just after OF_close()
 >  > another disk during zfs init/probe.
 >  > 2. do OF_seek(ihandle_t a) just after OF_open("available controller
 >  > without disk"). For example there is no disk3 on my machine though
 >  > there is disk controller. OF_open("disk3:") will report:
 >  > Can't read disk label.
 >  > Can't open disk label package
 >  > 
 >  > in ofw_disk.c, OF_close() has been commented out for powerpc
 >  > architecture, and can not find detail reason from code history, so I
 >  > am thinking if we need also disable OF_close() for sparc64.
 >  Hrm, some OFW implementations might have reference counting bugs,
 >  causing OF_close() to also close some parent(s) when these in fact
 >  are still used by another opened child device. Have you tried how
 >  it works when just commenting out the OF_close() in ofwd_close() but
 >  leaving the rest of ofw_disk.c as is? If that works, we probably
 >  can add a cleanup handler which closes all opened disk devices
 >  before leaving the loader, still taking advantage of caching opened
 >  disks.
 With the machines I have at hand, I can't reproduce this problem,
 i.e. ofw_disk.c as is works just fine for booting from a mirror.
 This suggests that what you are seeing actually is a bug in the
 specific firmware implementation rather than a general limitation
 imposed by OFW. Could you please give the following patch a try?
 It implements what I've described above, i.e. combines both caching
 opened devices and properly closing all opened disks when leaving
 the loader.

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