From owner-freebsd-bugs Thu Mar 2 0:10:28 2000 Delivered-To: freebsd-bugs@freebsd.org Received: from freefall.freebsd.org (freefall.FreeBSD.ORG [204.216.27.21]) by hub.freebsd.org (Postfix) with ESMTP id C9FCF37C3FC for ; Thu, 2 Mar 2000 00:10:05 -0800 (PST) (envelope-from gnats@FreeBSD.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.9.3/8.9.2) id AAA47290; Thu, 2 Mar 2000 00:10:05 -0800 (PST) (envelope-from gnats@FreeBSD.org) Date: Thu, 2 Mar 2000 00:10:05 -0800 (PST) Message-Id: <200003020810.AAA47290@freefall.freebsd.org> To: freebsd-bugs@FreeBSD.org Cc: From: jhood@sitaranetworks.com, cgull@owl.org Subject: kern/17098: /boot/loader hangs on switch to second drive Reply-To: jhood@sitaranetworks.com, cgull@owl.org Sender: owner-freebsd-bugs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org The following reply was made to PR kern/17098; it has been noted by GNATS. From: jhood@sitaranetworks.com, cgull@owl.org To: FreeBSD-gnats-submit@freebsd.org Cc: grog@lemis.com Subject: kern/17098: /boot/loader hangs on switch to second drive Date: Wed, 1 Mar 2000 13:24:19 -0500 (EST) >Number: 17098 >Category: kern >Synopsis: /boot/loader hangs on switch to second drive >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Mar 1 10:30:01 PST 2000 >Closed-Date: >Last-Modified: >Originator: John Hood >Release: FreeBSD 3.2-RELEASE i386 >Organization: Sitara Networks >Environment: i386 3.2-RELEASE + local mods, FreeBSD installs on two drives >Description: The boot loader often hangs when requested to boot a kernel from a drive other than the one it started from. >How-To-Repeat: Set up a system with boot environment & kernels on two "fast" drives, preferably of wildly different geometry and sizes. (Floppy I/O may be slow enough to cover up this problem.) Install the sample loader.rc on boot drive, editing as necessary. Reboot & wait forever, if you are lucky-- the bug is a bit shy sometimes. Sample loader.rc: \ Loader.rc \ 1 trace! set currdev=disk2s1a: \ Something other than $loaddev \ 11000 ms \ Uncomment this to get a working load \ show \ \ Includes additional commands include /boot/loader.4th \ Reads and processes loader.rc start \ Unless set otherwise, autoboot is automatic at this point >Fix: There are two problems here: the block cache code and (presumably) the UFS code. The block cache, as implemented, has no mechanism for distinguishing which device a block or block request is for. When a different device is selected, it may return a block from the wrong device. Debugging this was complicated by the 2s block discard timeout-- debugging printfs to a serial console would make the loader work, as would executing loader commands/words by hand :) Secondarily, when this happens, some other part of the loader reacts poorly to bogus data and hangs-- I'd guess that it's the UFS code, but I've not traced the problem. The block-cache problem exists in any version of the loader that has the block cache implemented. Minimalistic i386-only fix for the block-cache problem follows-- diffs are against a locally-modified 3.2-RELEASE. Since the loader's device architecture does not have a globally-visible way of referring to a specific device and unit, this appears to be the best way to pass the necessary info into the block cache, short of wholesale rearchitecting. --john hood diff -ur /sys/boot/common/bcache.c ./common/bcache.c --- /sys/boot/common/bcache.c Sat Feb 6 09:27:29 1999 +++ ./common/bcache.c Fri Feb 18 17:35:19 2000 @@ -23,7 +23,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: bcache.c,v 1.4.2.1 1999/02/06 14:27:29 dcs Exp $ + * $Id: bcache.c,v 1.2 2000/02/18 22:35:19 jhood Exp $ */ /* @@ -62,17 +62,33 @@ static int bcache_hits, bcache_misses, bcache_ops, bcache_bypasses; static int bcache_bcount; +static void *bcache_dkstrategy; +static int bcache_dkunit; + static void bcache_insert(caddr_t buf, daddr_t blkno); static int bcache_lookup(caddr_t buf, daddr_t blkno); /* + * Invalidate the cache + */ +void +bcache_flush(void) +{ + int i; + + if (bcache_data != NULL) { + for (i = 0; i < bcache_nblks; i++) { + bcache_ctl[i].bc_count = -1; + bcache_ctl[i].bc_blkno = -1; + } + } +} +/* * Initialise the cache for (nblks) of (bsize). */ int bcache_init(int nblks, size_t bsize) { - int i; - /* discard any old contents */ if (bcache_data != NULL) { free(bcache_data); @@ -97,11 +113,9 @@ return(ENOMEM); } - /* Invalidate the cache */ - for (i = 0; i < bcache_nblks; i++) { - bcache_ctl[i].bc_count = -1; - bcache_ctl[i].bc_blkno = -1; - } + bcache_dkstrategy = NULL; + + /* bcache_flush() will happen on first call to bcache_strategy */ return(0); } @@ -130,6 +144,16 @@ DEBUG("bypass %d from %d", size / bcache_blksize, blk); bcache_bypasses++; return(dd->dv_strategy(dd->dv_devdata, rw, blk, size, buf, rsize)); + } + + /* has a new device/unit been requested? flush cache */ + if ((bcache_dkstrategy != dd->dv_strategy) || + (bcache_dkunit != dd->dv_dkunit)) { + DEBUG("cache flush, lastunit = %d newunit = %d", + bcache_dkunit, dd->dv_dkunit); + bcache_flush(); + bcache_dkstrategy = dd->dv_strategy; + bcache_dkunit = dd->dv_dkunit; } nblk = size / bcache_blksize; diff -ur /sys/boot/common/bootstrap.h ./common/bootstrap.h --- /sys/boot/common/bootstrap.h Sat Feb 6 09:27:29 1999 +++ ./common/bootstrap.h Fri Feb 18 17:35:20 2000 @@ -23,7 +23,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: bootstrap.h,v 1.18.2.1 1999/02/06 14:27:29 dcs Exp $ + * $Id: bootstrap.h,v 1.2 2000/02/18 22:35:20 jhood Exp $ */ #include @@ -84,6 +84,7 @@ struct bcache_devdata { int (*dv_strategy)(void *devdata, int rw, daddr_t blk, size_t size, void *buf, size_t *rsize); + int dv_dkunit; void *dv_devdata; }; diff -ur /sys/boot/i386/libi386/biosdisk.c ./i386/libi386/biosdisk.c --- /sys/boot/i386/libi386/biosdisk.c Tue Mar 16 09:58:25 1999 +++ ./i386/libi386/biosdisk.c Fri Feb 18 17:35:47 2000 @@ -23,7 +23,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: biosdisk.c,v 1.20.2.4 1999/03/16 14:58:25 dcs Exp $ + * $Id: biosdisk.c,v 1.3 2000/02/18 22:35:47 jhood Exp $ */ /* @@ -573,6 +575,8 @@ struct bcache_devdata bcd; bcd.dv_strategy = bd_realstrategy; + bcd.dv_dkunit = ((struct open_disk *)(((struct i386_devdesc *) + devdata)->d_kind.biosdisk.data))->od_dkunit; bcd.dv_devdata = devdata; return(bcache_strategy(&bcd, rw, dblk, size, buf, rsize)); } >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message