[v6,13/14] arm64, acpi, numa: NUMA support based on SRAT and SLIT

Message ID 20160512162449.GK11226@e104818-lin.cambridge.arm.com
State New
Headers show

Commit Message

Catalin Marinas May 12, 2016, 4:24 p.m.
On Thu, May 12, 2016 at 08:27:08AM -0700, David Daney wrote:
> On 05/12/2016 02:49 AM, Catalin Marinas wrote:

> >On Wed, May 11, 2016 at 05:06:13PM -0700, David Daney wrote:

> >>On 05/11/2016 03:39 AM, Catalin Marinas wrote:

> [...]

> >>>

> >>>I wonder whether you could replace the get_mpidr_in_madt() function with

> >>>something like acpi_get_phys_id(). It looks like get_mpidr_in_madt()

> >>>duplicates functionality already available elsewhere.

> >>

> >>I just tried that, and it doesn't work.

> >>

> >>The problem is that this code is being run very early in the boot, and

> >>kmalloc cannot be used.  acpi_get_phys_id() and its ilk can only be used

> >>once we have working kmalloc.  We need to extract the NUMA information early

> >>like this precisely because it is needed to initializing the slab system

> >>

> >>Notice that we are using early_acpi_os_unmap_memory() et al. in

> >>get_mpidr_in_madt() explicitly for this reason.

> >>

> >>In summary: I don't think we need another revision of this patch, it is like

> >>this for a good reason.

> >

> >Slightly confusing, in another reply you said you are going to address

> >my comment. So, is it doable?


> I don't think so.


> My previous reply, to the thread in 0/14, was prematurely made with the

> incorrect assumption that it was a simple change.  Now, after really digging

> in to the code, and attempting to do as you suggested, I have changed my

> mind.

Would the snippet below help with avoiding any kmalloc calls? At a quick
look, it seems that it's only map_mat_entry() that ends up using
kmalloc() calls. Alternatively, exporting map_madt_entry() may work as

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diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 33a38d604630..77af0a7df914 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -152,6 +152,9 @@  static phys_cpuid_t map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
 	struct acpi_subtable_header *header;
 	phys_cpuid_t phys_id = PHYS_CPUID_INVALID;
+	if (!acpi_gbl_permanent_mmap)
+		return phys_id;
 	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
 		goto exit;