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Prefault bus pages in driver attachment. This seems to work around 

weird corruption I've been seeing (most likely a host kernel bug).

For more details, see thread at:
http://mail-index.netbsd.org/tech-kern/2010/08/17/msg008749.html
This commit is contained in:
pooka 2010-08-17 20:42:47 +00:00
parent 3bc68298fb
commit 942c727880
1 changed files with 30 additions and 2 deletions
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32
sys/rump/net/lib/libshmif/if_shmem.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: if_shmem.c,v 1.27 2010/08/17 11:35:23 pooka Exp $ */
/* $NetBSD: if_shmem.c,v 1.28 2010/08/17 20:42:47 pooka Exp $ */
/*
* Copyright (c) 2009 Antti Kantee. All Rights Reserved.
@ -28,7 +28,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_shmem.c,v 1.27 2010/08/17 11:35:23 pooka Exp $");
__KERNEL_RCSID(0, "$NetBSD: if_shmem.c,v 1.28 2010/08/17 20:42:47 pooka Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@ -50,6 +50,16 @@ __KERNEL_RCSID(0, "$NetBSD: if_shmem.c,v 1.27 2010/08/17 11:35:23 pooka Exp $");
#include "rump_private.h"
#include "rump_net_private.h"
/*
* Do r/w prefault for backend pages when attaching the interface.
* This works aroud the most likely kernel/ffs/x86pmap bug described
* in http://mail-index.netbsd.org/tech-kern/2010/08/17/msg008749.html
*
* NOTE: read prefaulting is not enough (that's done always)!
*/
#define PREFAULT_RW
/*
* A virtual ethernet interface which uses shared memory from a
* memory mapped file as the bus.
@ -127,6 +137,8 @@ rump_shmif_create(const char *path, int *ifnum)
uint8_t enaddr[ETHER_ADDR_LEN] = { 0xb2, 0xa0, 0x00, 0x00, 0x00, 0x00 };
uint32_t randnum;
unsigned mynum;
volatile uint8_t v;
volatile uint8_t *p;
int error;
randnum = arc4random();
@ -149,6 +161,13 @@ rump_shmif_create(const char *path, int *ifnum)
if (sc->sc_busmem->shm_magic && sc->sc_busmem->shm_magic != SHMIF_MAGIC)
panic("bus is not magical");
/* Prefault in pages to minimize runtime penalty with buslock */
for (p = (uint8_t *)sc->sc_busmem;
p < (uint8_t *)sc->sc_busmem + BUSMEM_SIZE;
p += PAGE_SIZE)
v = *p;
shmif_lockbus(sc->sc_busmem);
/* we're first? initialize bus */
if (sc->sc_busmem->shm_magic == 0) {
@ -158,6 +177,15 @@ rump_shmif_create(const char *path, int *ifnum)
sc->sc_nextpacket = sc->sc_busmem->shm_last;
sc->sc_devgen = sc->sc_busmem->shm_gen;
#ifdef PREFAULT_RW
for (p = (uint8_t *)sc->sc_busmem;
p < (uint8_t *)sc->sc_busmem + BUSMEM_SIZE;
p += PAGE_SIZE) {
v = *p;
*p = v;
}
#endif
shmif_unlockbus(sc->sc_busmem);
sc->sc_kq = rumpuser_writewatchfile_setup(-1, sc->sc_memfd, 0, &error);