sparc64/164226: Data corruption on 9.0-RELEASE when reading from CDROM

[C. P. Ghost]

>Number:         164226
>Category:       sparc64
>Synopsis:       Data corruption on 9.0-RELEASE when reading from CDROM
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-sparc64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Jan 17 00:40:07 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     C. P. Ghost
>Release:        FreeBSD 9.0-RELEASE/sparc64
>Organization:
Cordula's Web
>Environment:
FreeBSD tarazed.cordula.ws 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Mon Jan 16 01:51:15 CET 2012     root at tarazed.cordula.ws:/usr/obj/usr/src/sys/GENERIC  sparc64
>Description:
It's not possible to install FreeBSD 9.0-RELEASE from CDROM on
a Blade 1500, because bsdinstall reports a corrupt base.txz.

Investigating the issue further, revealed that the 9.0 kernel
corrupts data read from a CDROM mounted via /dev/cd0, while
the 8.2 kernel doesn't corrupt data when the CDROM is mounted
via /dev/acd0.

>How-To-Repeat:
8.2-RELEASE doesn't exhibit the bug:

1. Install 8.2-RELEASE on a sun4u system.
2. Mount the 9.0-RELEASE CDROM (using /dev/acd0)
3. cd /cdrom/usr/freebsd-dist; sha256 *.txz;
4. compare with MANIFEST -> same checksums.

Upgrade to 9.0-RELEASE, e.g. from source:

4. mv /usr/src /usr/src.82
5. cd /; tar -xvpf /cdrom/usr/freebsd-dist/src.txz
6. source upgrade from 8.2 to 9.0

9.0-RELEASE exhibits the problem:

7. Reboot to 9.0-RELEASE
8. Mount the 9.0-RELEASE CDROM (using /dev/cd0)
9. cd /cdrom/usr/freebsd-dist; sha256 *.txz
10. compare checksums with MANIFEST -> different checksums!

Reboot 9.0 userland to 8.2 (/boot/kernel.old/kernel)
and repeat sha256 checksums -> no errors.

Note, the sha256 program on 9.0 yields the same checksums
on arbitrary files than on 8.2, as long as those files are
not read from CDROM (e.g. fetched from the net). It is okay.
>Fix:
No fix known yet.

Workaround: netboot 9.0, or source-upgrade from a previous
release. Don't use CDROM (/dev/cd0) on 9.0 until this bug
is fixed.

>Release-Note:
>Audit-Trail:
>Unformatted: