On Thu, May 12, 2016 at 08:27:08AM -0700, David Daney wrote:

On 05/12/2016 02:49 AM, Catalin Marinas wrote:

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

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

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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
well.

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;
 

-- 
Catalin