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Revision 4dc2287c1805e7fe8a7cb90bbcd44abee8cdb914 authored by Bjorn Helgaas on 16 December 2010, 17:38:56 UTC, committed by Jesse Barnes on 17 December 2010, 18:01:24 UTC 
x86: avoid E820 regions when allocating address space
 
When we allocate address space, e.g., to assign it to a PCI device, don't
allocate anything mentioned in the BIOS E820 memory map.

On recent machines (2008 and newer), we assign PCI resources from the
windows described by the ACPI PCI host bridge _CRS.  On many Dell
machines, these windows overlap some E820 reserved areas, e.g.,

    BIOS-e820: 00000000bfe4dc00 - 00000000c0000000 (reserved)
    pci_root PNP0A03:00: host bridge window [mem 0xbff00000-0xdfffffff]

If we put devices at 0xbff00000, they don't work, probably because
that's really RAM, not I/O memory.  This patch prevents that by removing
the 0xbfe4dc00-0xbfffffff area from the "available" resource.

I'm not very happy with this solution because Windows solves the problem
differently (it seems to ignore E820 reserved areas and it allocates
top-down instead of bottom-up; details at comment 45 of the bugzilla
below).  That means we're vulnerable to BIOS defects that Windows would not
trip over.  For example, if BIOS described a device in ACPI but didn't
mention it in E820, Windows would work fine but Linux would fail.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
1 parent 30919b0
Raw File
pkt_sched.h 
#ifndef __NET_PKT_SCHED_H
#define __NET_PKT_SCHED_H

#include <linux/jiffies.h>
#include <linux/ktime.h>
#include <net/sch_generic.h>

struct qdisc_walker {
	int	stop;
	int	skip;
	int	count;
	int	(*fn)(struct Qdisc *, unsigned long cl, struct qdisc_walker *);
};

#define QDISC_ALIGNTO		64
#define QDISC_ALIGN(len)	(((len) + QDISC_ALIGNTO-1) & ~(QDISC_ALIGNTO-1))

static inline void *qdisc_priv(struct Qdisc *q)
{
	return (char *) q + QDISC_ALIGN(sizeof(struct Qdisc));
}

/* 
   Timer resolution MUST BE < 10% of min_schedulable_packet_size/bandwidth
   
   Normal IP packet size ~ 512byte, hence:

   0.5Kbyte/1Mbyte/sec = 0.5msec, so that we need 50usec timer for
   10Mbit ethernet.

   10msec resolution -> <50Kbit/sec.
   
   The result: [34]86 is not good choice for QoS router :-(

   The things are not so bad, because we may use artifical
   clock evaluated by integration of network data flow
   in the most critical places.
 */

typedef u64	psched_time_t;
typedef long	psched_tdiff_t;

/* Avoid doing 64 bit divide */
#define PSCHED_SHIFT			6
#define PSCHED_TICKS2NS(x)		((s64)(x) << PSCHED_SHIFT)
#define PSCHED_NS2TICKS(x)		((x) >> PSCHED_SHIFT)

#define PSCHED_TICKS_PER_SEC		PSCHED_NS2TICKS(NSEC_PER_SEC)
#define PSCHED_PASTPERFECT		0

static inline psched_time_t psched_get_time(void)
{
	return PSCHED_NS2TICKS(ktime_to_ns(ktime_get()));
}

static inline psched_tdiff_t
psched_tdiff_bounded(psched_time_t tv1, psched_time_t tv2, psched_time_t bound)
{
	return min(tv1 - tv2, bound);
}

struct qdisc_watchdog {
	struct hrtimer	timer;
	struct Qdisc	*qdisc;
};

extern void qdisc_watchdog_init(struct qdisc_watchdog *wd, struct Qdisc *qdisc);
extern void qdisc_watchdog_schedule(struct qdisc_watchdog *wd,
				    psched_time_t expires);
extern void qdisc_watchdog_cancel(struct qdisc_watchdog *wd);

extern struct Qdisc_ops pfifo_qdisc_ops;
extern struct Qdisc_ops bfifo_qdisc_ops;
extern struct Qdisc_ops pfifo_head_drop_qdisc_ops;

extern int fifo_set_limit(struct Qdisc *q, unsigned int limit);
extern struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
				      unsigned int limit);

extern int register_qdisc(struct Qdisc_ops *qops);
extern int unregister_qdisc(struct Qdisc_ops *qops);
extern void qdisc_list_del(struct Qdisc *q);
extern struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle);
extern struct Qdisc *qdisc_lookup_class(struct net_device *dev, u32 handle);
extern struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
		struct nlattr *tab);
extern void qdisc_put_rtab(struct qdisc_rate_table *tab);
extern void qdisc_put_stab(struct qdisc_size_table *tab);
extern void qdisc_warn_nonwc(char *txt, struct Qdisc *qdisc);
extern int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
			   struct net_device *dev, struct netdev_queue *txq,
			   spinlock_t *root_lock);

extern void __qdisc_run(struct Qdisc *q);

static inline void qdisc_run(struct Qdisc *q)
{
	if (qdisc_run_begin(q))
		__qdisc_run(q);
}

extern int tc_classify_compat(struct sk_buff *skb, struct tcf_proto *tp,
			      struct tcf_result *res);
extern int tc_classify(struct sk_buff *skb, struct tcf_proto *tp,
		       struct tcf_result *res);

/* Calculate maximal size of packet seen by hard_start_xmit
   routine of this device.
 */
static inline unsigned psched_mtu(const struct net_device *dev)
{
	return dev->mtu + dev->hard_header_len;
}

#endif
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