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Fix a problem that caused system crashes after physio. This problem

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was due to non-aligned 64K transfers taking 17 pages.  We currently
do not support >16 page transfers.  The transfer is unfortunately truncated,
but since buffers are usually malloced, this is a problem only once in
a while.  Savecore is a culprit, but tar/cpio usually aren't.  This
is NOT the final fix (which is likely a bouncing scheme), but will at
least keep the system from crashing.
This commit is contained in:
John Dyson 1996-06-26 05:52:15 +00:00
parent 89cabf65de
commit 4b83b27fea
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=16752
1 changed files with 11 additions and 6 deletions
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17
sys/kern/kern_physio.c
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@ -16,7 +16,7 @@
* 4. Modifications may be freely made to this file if the above conditions
* are met.
*
* $Id: kern_physio.c,v 1.15 1995/12/07 12:46:46 davidg Exp $
* $Id: kern_physio.c,v 1.16 1995/12/13 15:12:59 julian Exp $
*/
#include <sys/param.h>
@ -78,13 +78,13 @@ physio(strategy, bp, dev, rw, minp, uio)
while( uio->uio_iov[i].iov_len) {
bp->b_bcount = uio->uio_iov[i].iov_len;
bp->b_flags = B_BUSY | B_PHYS | B_CALL | bufflags;
bp->b_iodone = physwakeup;
bp->b_data = uio->uio_iov[i].iov_base;
bp->b_bcount = minp( bp);
if( minp != minphys)
bp->b_bcount = minphys( bp);
bp->b_bufsize = bp->b_bcount;
bp->b_flags = B_BUSY | B_PHYS | B_CALL | bufflags;
bp->b_iodone = physwakeup;
bp->b_data = uio->uio_iov[i].iov_base;
/*
* pass in the kva from the physical buffer
* for the temporary kernel mapping.
@ -164,9 +164,14 @@ doerror:
u_int
minphys(struct buf *bp)
{
u_int maxphys = MAXPHYS;
if( bp->b_bcount > MAXPHYS) {
bp->b_bcount = MAXPHYS;
if( ((vm_offset_t) bp->b_data) & PAGE_MASK) {
maxphys = MAXPHYS - PAGE_SIZE;
}
if( bp->b_bcount > maxphys) {
bp->b_bcount = maxphys;
}
return bp->b_bcount;
}