Re: [Bug 16228] BUG/boot failure on Dell Precision T3500 (pci/ahci_stop_engine)
From: Yinghai Lu
Date: Thu Jun 17 2010 - 14:43:49 EST
On 06/17/2010 09:37 AM, bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=16228
>
>
> Bjorn Helgaas <bjorn.helgaas@xxxxxx> changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |yinghai@xxxxxxxxxx
>
>
>
>
> --- Comment #8 from Bjorn Helgaas <bjorn.helgaas@xxxxxx> 2010-06-17 16:37:42 ---
> That's perfect, thanks!
>
> The E820 memory map from BIOS reports a range that overlaps the first
> megabyte (0xbff00000-0xbfffffff) of that host bridge window:
>
> BIOS-e820: 0000000000100000 - 00000000bfdf9c00 (usable)
> BIOS-e820: 00000000bfdf9c00 - 00000000bfe4bc00 (ACPI NVS)
> BIOS-e820: 00000000bfe4bc00 - 00000000bfe4dc00 (ACPI data)
> BIOS-e820: 00000000bfe4dc00 - 00000000c0000000 (reserved)
> pci_root PNP0A03:00: host bridge window [mem 0xbff00000-0xdfffffff]
>
> The 0x100000-0xbfdf9c00 range is system RAM, and I would expect that
> the ACPI NVS and data area is also RAM, and the last reserved piece is
> probably RAM, too, because RAM tends to end at nicely aligned boundaries.
>
> Table 14-1 in the ACPI 4.0 spec says "reserved" ranges from the E820
> table are "unsuitable for a standard device to use as a device memory
> space."
>
> I think maybe Linux should regard those reserved ranges as unavailable
> for allocation to PCI devices, even if they happen to be included in a
> host bridge window. What do you think, Yinghai?
for above 1M area,
current kernel will honor setting from HW register and later will use insert_resource_expand_to_fit()
with e820 reserved entries.
so in this case will have one big 0xbfe4dc00 - 0xe000000 reserved entry in /proc/iomem as parent of
0xbff00000 - 0xe0000000
Sane BIOS should not put allocated range to PCI bridge/device into e820 table as reserved entries.
But there IS some BIOS doing that.
So Linus decided to trust setting from PCI bar at first.
later for pci_assign_unsigned, We should avoid those range.
one solution is expanding my one of old version for below 1M handling to:
use reserve_region_with_split instead.
will get /proc/iomem
bfe4dc00 - bfefffff reserved
bff00000 - dfffffff PCI BUS #00
bff00000 - bfffffff reserved
...
so will use bff0000 - bfffffff reserved as holder to prevent those range to be allocated to unassigned devices.
reserve_region_with_split need to need be updated a little bit to make sure it will not put holder on range with children already.
something like this
Subject: [PATCH] x86, resource: Add reserve_region_with_split_check_child()
It will cover the whole region to BUSY, except that some regions that have
children under them.
those children normally is PCI bar but it is falling into E820_RESERVED.
We can not put BUSY on them, otherwise driver can not use pci_request_region()
later
/proc/iomem will have
00010000-00094fff : System RAM
00095000-0009ffff : reserved
000a0000-000bffff : PCI Bus 0000:00
000a0000-000bffff : reserved
000c0000-000cffff : reserved
000d0000-000dffff : PCI Bus 0000:00
000d0000-000dffff : reserved
000e0000-000fffff : reserved
-v2: Add function pointer to put string comparing with caller
-v3: expand to use it above 1M resources.
Tested-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
Tested-by: Andy Isaacson <adi@xxxxxxxxxxxxx>
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
arch/x86/kernel/e820.c | 15 ++++++++++++---
include/linux/ioport.h | 3 +++
kernel/resource.c | 29 ++++++++++++++++++++++++-----
3 files changed, 39 insertions(+), 8 deletions(-)
Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -1094,7 +1094,7 @@ void __init e820_reserve_resources(void)
* pci device BAR resource and insert them later in
* pcibios_resource_survey()
*/
- if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) {
+ if (e820.map[i].type != E820_RESERVED) {
res->flags |= IORESOURCE_BUSY;
insert_resource(&iomem_resource, res);
}
@@ -1128,6 +1128,14 @@ static unsigned long ram_alignment(resou
#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
+static int __init check_func(struct resource *cf)
+{
+ if (strstr(cf->name, "PCI Bus"))
+ return 1;
+
+ return 0;
+}
+
void __init e820_reserve_resources_late(void)
{
int i;
@@ -1135,8 +1143,9 @@ void __init e820_reserve_resources_late(
res = e820_res;
for (i = 0; i < e820.nr_map; i++) {
- if (!res->parent && res->end)
- insert_resource_expand_to_fit(&iomem_resource, res);
+ if (!res->parent && res->end) {
+ reserve_region_with_split_check_child(&iomem_resource, res->start, res->end, res->name, check_func);
+ }
res++;
}
Index: linux-2.6/include/linux/ioport.h
===================================================================
--- linux-2.6.orig/include/linux/ioport.h
+++ linux-2.6/include/linux/ioport.h
@@ -120,6 +120,9 @@ void release_child_resources(struct reso
extern void reserve_region_with_split(struct resource *root,
resource_size_t start, resource_size_t end,
const char *name);
+void reserve_region_with_split_check_child(struct resource *root,
+ resource_size_t start, resource_size_t end,
+ const char *name, int (*check_func)(struct resource *cf));
extern struct resource *insert_resource_conflict(struct resource *parent, struct resource *new);
extern int insert_resource(struct resource *parent, struct resource *new);
extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new);
Index: linux-2.6/kernel/resource.c
===================================================================
--- linux-2.6.orig/kernel/resource.c
+++ linux-2.6/kernel/resource.c
@@ -607,9 +607,14 @@ int adjust_resource(struct resource *res
return result;
}
+static int __init check_func_nop(struct resource *cf)
+{
+ return 1;
+}
+
static void __init __reserve_region_with_split(struct resource *root,
resource_size_t start, resource_size_t end,
- const char *name)
+ const char *name, bool check_child, int (*check_func)(struct resource *cf))
{
struct resource *parent = root;
struct resource *conflict;
@@ -631,13 +636,18 @@ static void __init __reserve_region_with
kfree(res);
/* conflict covered whole area */
- if (conflict->start <= start && conflict->end >= end)
+ if (conflict->start <= start && conflict->end >= end) {
+ if (check_child && !conflict->child && check_func(conflict))
+ __reserve_region_with_split(conflict, start, end, name, false, check_func_nop);
return;
+ }
if (conflict->start > start)
- __reserve_region_with_split(root, start, conflict->start-1, name);
+ __reserve_region_with_split(root, start, conflict->start-1, name, check_child, check_func);
if (conflict->end < end)
- __reserve_region_with_split(root, conflict->end+1, end, name);
+ __reserve_region_with_split(root, conflict->end+1, end, name, check_child, check_func);
+ if (check_child && !conflict->child && check_func(conflict))
+ __reserve_region_with_split(conflict, conflict->start, conflict->end, name, false, check_func_nop);
}
void __init reserve_region_with_split(struct resource *root,
@@ -645,7 +655,16 @@ void __init reserve_region_with_split(st
const char *name)
{
write_lock(&resource_lock);
- __reserve_region_with_split(root, start, end, name);
+ __reserve_region_with_split(root, start, end, name, false, check_func_nop);
+ write_unlock(&resource_lock);
+}
+
+void __init reserve_region_with_split_check_child(struct resource *root,
+ resource_size_t start, resource_size_t end,
+ const char *name, int (*check_func)(struct resource *cf))
+{
+ write_lock(&resource_lock);
+ __reserve_region_with_split(root, start, end, name, true, check_func);
write_unlock(&resource_lock);
}
--
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