Re: [PATCH] Add IORESOUCE_BUSY flag for System RAM (Re: [Question]

Badari Pulavarty
2007-11-01T15:25:00Z

On Thu, 2007-11-01 at 18:21 +0900, Yasunori Goto wrote:
> Hello.
>
> I was asked from Kame-san to write this patch.
>
> Please apply.
>
> ---------
> i386 and x86-64 registers System RAM as IORESOURCE_MEM | IORESOURCE_BUSY.
>
> But ia64 registers it as IORESOURCE_MEM only.
> In addition, memory hotplug code registers new memory as IORESOURCE_MEM too.
>
> This patch adds IORESOURCE_BUSY for them to avoid potential overlap mapping
> by PCI device.
>
> Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
>
> ---
> arch/ia64/kernel/efi.c | 6 ++----
> mm/memory_hotplug.c | 2 +-
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> Index: current/arch/ia64/kernel/efi.c
> =================================> --- current.orig/arch/ia64/kernel/efi.c 2007-11-01 15:24:05.000000000 +0900
> +++ current/arch/ia64/kernel/efi.c 2007-11-01 15:24:18.000000000 +0900
> @@ -1111,7 +1111,7 @@ efi_initialize_iomem_resources(struct re
> if (md->num_pages = 0) /* should not happen */
> continue;
>
> - flags = IORESOURCE_MEM;
> + flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> switch (md->type) {
>
> case EFI_MEMORY_MAPPED_IO:
> @@ -1133,12 +1133,11 @@ efi_initialize_iomem_resources(struct re
>
> case EFI_ACPI_MEMORY_NVS:
> name = "ACPI Non-volatile Storage";
> - flags |= IORESOURCE_BUSY;
> break;
>
> case EFI_UNUSABLE_MEMORY:
> name = "reserved";
> - flags |= IORESOURCE_BUSY | IORESOURCE_DISABLED;
> + flags |= IORESOURCE_DISABLED;
> break;
>
> case EFI_RESERVED_TYPE:
> @@ -1147,7 +1146,6 @@ efi_initialize_iomem_resources(struct re
> case EFI_ACPI_RECLAIM_MEMORY:
> default:
> name = "reserved";
> - flags |= IORESOURCE_BUSY;
> break;
> }
>
> Index: current/mm/memory_hotplug.c
> =================================> --- current.orig/mm/memory_hotplug.c 2007-11-01 15:24:16.000000000 +0900
> +++ current/mm/memory_hotplug.c 2007-11-01 15:41:27.000000000 +0900
> @@ -39,7 +39,7 @@ static struct resource *register_memory_
> res->name = "System RAM";
> res->start = start;
> res->end = start + size - 1;
> - res->flags = IORESOURCE_MEM;
> + res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> if (request_resource(&iomem_resource, res) < 0) {
> printk("System RAM resource %llx - %llx cannot be added\n",
> (unsigned long long)res->start, (unsigned long long)res->end);
>

Not quite.. You need following patch on top of this to make
hotplug memory remove work on ia64/x86-64.

Thanks,
Badari

Once you mark memory resource BUSY, walk_memory_resource() won't be able
to find it.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
---
kernel/resource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.24-rc1/kernel/resource.c
=================================--- linux-2.6.24-rc1.orig/kernel/resource.c 2007-10-23 20:50:57.000000000 -0700
+++ linux-2.6.24-rc1/kernel/resource.c 2007-11-01 08:19:59.000000000 -0700
@@ -277,7 +277,7 @@ walk_memory_resource(unsigned long start
int ret = -1;
res.start = (u64) start_pfn << PAGE_SHIFT;
res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
- res.flags = IORESOURCE_MEM;
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
orig_end = res.end;
while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
pfn = (unsigned long)(res.start >> PAGE_SHIFT);