Hi greg,

On 10/08/2017 09:06, Greg Ungerer wrote:
Hi Angelo,

On 10/08/17 01:32, Angelo Dureghello wrote:
[snip]
sure, on this board  http://sysam.it/cff_stmark2.html
there are 128MB of ddr2.

External SDRAM is accessible, at least without any mmc support enabled,
from 0x40000000.

I have following test config:

   GNU nano 2.8.6                                                               
               File: arch/m68k/configs/stmark2_defconfig

CONFIG_LOCALVERSION="stmark2-001"
[snip]


I tried still yesterday a bit, but seems there is no much support for
earlyprintk / low level debug for this architecture.

In case i can try with a gpio toggling routine, at least to find
where kernel stops.

The attached patch, is a quick and dirty early console output method.
It works for me on the m5475, should work for you "as is" on the 5441x too.

It is kind of an early printk. Of course it still needs the early
kernel boot to have succeeded before you will get anything much coming out.
But it is worth trying.

I am wondering if the non-0 base RAM may be a problem. I have only run
the MMU enabled code on platforms with 0 based RAM so far. But lets see if
the early console trace attached gives us anything before digging into that.


I have some news, found the exact point where the kernel stops,
it is a " panic("Out of memory");" but you can check
the comments in the diff below to see what exactly happen:

iff --git a/mm/bootmem.c b/mm/bootmem.c
index 9fedb27c6451..2bf51bf1bf28 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -20,6 +20,8 @@
#include "internal.h" +extern void __square(void);
+
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 struct pglist_data __refdata contig_page_data = {
        .bdata = &bootmem_node_data[0]
@@ -501,6 +503,8 @@ static void * __init alloc_bootmem_bdata(struct 
bootmem_data *bdata,
        unsigned long fallback = 0;
        unsigned long min, max, start, sidx, midx, step;
+ /* we don't even enter here */
+
        bdebug("nid=%td size=%lx [%lu pages] align=%lx goal=%lx limit=%lx\n",
                bdata - bootmem_node_data, size, PAGE_ALIGN(size) >> PAGE_SHIFT,
                align, goal, limit);
@@ -539,6 +543,7 @@ static void * __init alloc_bootmem_bdata(struct 
bootmem_data *bdata,
                 * catch the fallback below.
                 */
                fallback = sidx + 1;
+
                sidx = align_idx(bdata, bdata->hint_idx, step);
        }
@@ -609,12 +614,18 @@ static void * __init alloc_bootmem_core(unsigned long size,
        bootmem_data_t *bdata;
        void *region;
+ /* we pass from here */
        if (WARN_ON_ONCE(slab_is_available()))
                return kzalloc(size, GFP_NOWAIT);
+ /* we pass from here */
        list_for_each_entry(bdata, &bdata_list, list) {
+
+               /* we never enter here */
+
                if (goal && bdata->node_low_pfn <= PFN_DOWN(goal))
                        continue;
+
                if (limit && bdata->node_min_pfn >= PFN_DOWN(limit))
                        break;
@@ -623,6 +634,8 @@ static void * __init alloc_bootmem_core(unsigned long size,
                        return region;
        }
+ /* we pass from here */
+
        return NULL;
 }
@@ -637,11 +650,18 @@ static void * __init ___alloc_bootmem_nopanic(unsigned long size,
        ptr = alloc_bootmem_core(size, align, goal, limit);
        if (ptr)
                return ptr;
+
+       /* alloc_bootmem_core returns null, ptr = 0 */
+
        if (goal) {
                goal = 0;
                goto restart;
+
+               /* we pass from here yes */
        }
+ /* we pass from here yes */
+
        return NULL;
 }
@@ -677,7 +697,10 @@ static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
         * Whoops, we cannot satisfy the allocation request.
         */
        pr_alert("bootmem alloc of %lu bytes failed!\n", size);
+
+       /* we finally stop here */
        panic("Out of memory");
+
        return NULL;
 }


So trying now to understand why that

list_for_each_entry(bdata, &bdata_list, list)

looks as an emtty list.

Regards,
Angelo



Regards
Greg

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