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Date: Wed, 14 Apr 2010 10:21:17 -0700
From: Yinghai Lu <yinghai.lu@...cle.com>
To: Bjorn Helgaas <bjorn.helgaas@...com>
CC: "H. Peter Anvin" <hpa@...or.com>,
Andy Isaacson <adi@...apodia.org>, guenter.roeck@...csson.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"x86@...nel.org" <x86@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map
On 04/14/2010 09:55 AM, Bjorn Helgaas wrote:
> On Tuesday 13 April 2010 06:57:54 pm Yinghai wrote:
>
>
>> 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
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>
>> ---
>> arch/x86/kernel/e820.c | 10 +++++++---
>> include/linux/ioport.h | 3 +++
>> kernel/resource.c | 24 +++++++++++++++++++-----
>> 3 files changed, 29 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);
>> }
>> @@ -1135,8 +1135,12 @@ 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) {
>> + if (res->start < (1ULL<<20)) {
>> + reserve_region_with_split_check_child(&iomem_resource, res->start, res->end, res->name);
>> + } else
>> + insert_resource_expand_to_fit(&iomem_resource, res);
>>
> I don't like adding all these special-purpose resource interfaces, e.g.,
> insert_resource_expand_to_fit(), reserve_region_with_split(),
> reserve_region_with_split_check_child(), etc. They tend to be only
> used by one caller, which is a clue to me that we're doing something
> wrong.
>
> Sometimes we'd like to print debug information in them (as we do in
> insert_resource_expand_to_fit()), but we don't have enough context,
> so the message isn't very meaningful.
>
print out related resource tree segment ?
> I think it's better to have more generic interfaces that allow us to
> implement this sort of functionality where it's used and where we
> have the context to print useful messages. For example, could the
> reserve_region_with_split_check_child() functionality be implemented
> in e820.c by building on something like request_resource_conflict()?
>
>
>> + }
>> 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);
>> 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
>> @@ -609,7 +609,7 @@ int adjust_resource(struct resource *res
>>
>> 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)
>> {
>> struct resource *parent = root;
>> struct resource *conflict;
>> @@ -631,13 +631,18 @@ 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 && strstr(conflict->name, "PCI Bus"))
>>
> This is kind of gross, too. Checking the name of a resource for "PCI Bus"?
>
yes, in case some system have device on BUS 0 directly. but have device
have pci BAR below 1M and fall into E820_RESERVED.
YH
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