On Fri, Jan 03, 2014 at 06:49:09PM -0600, Scott Wood wrote:

On Fri, 2013-12-20 at 15:43 +0800, Kevin Hao wrote:

quoted

On Wed, Dec 18, 2013 at 05:48:25PM -0600, Scott Wood wrote:

quoted

On Wed, Aug 07, 2013 at 09:18:31AM +0800, Kevin Hao wrote:

quoted

This is based on the codes in the head_44x.S. The difference is that
the init tlb size we used is 64M. With this patch we can only load the
kernel at address between memstart_addr ~ memstart_addr + 64M. We will
fix this restriction in the following patches.

Which following patch fixes the restriction?  With all seven patches
applied, I was still only successful booting within 64M of memstart_addr.

There is bug in this patch series when booting above the 64M. It seems
that I missed to test this previously. Sorry for that. With the following
change I can boot the kernel at 0x5000000.

I tried v4 and it still doesn't work for me over 64M (without increasing
the start of memory).  I pulled the following out of the log buffer when
booting at 0x5000000 (after cleaning up the binary goo -- is that
something new?):

Unable to handle kernel paging request for data at address 0xbffe4008

Actually there still have one limitation that we have to make sure
that the kernel and dtb are in the 64M memory mapped by the init tlb entry.
I booted the kernel successfully by using the following u-boot commands:
  setenv fdt_high 0xffffffff
  dhcp 6000000 128.224.162.196:/vlm-boards/p5020/uImage
  tftp 6f00000 128.224.162.196:/vlm-boards/p5020/p5020ds.dtb
  bootm 6000000 - 6f00000                                                                                                                                         

Faulting instruction address: 0xc16ee934
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=8
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 3.13.0-rc1-00065-g422752a #12
task: c18f2340 ti: c192c000 task.ti: c192c000
NIP: c16ee934 LR: c16d1860 CTR: c100e96c
REGS: c192dee0 TRAP: 0300   Not tainted  (3.13.0-rc1-00065-g422752a)
MSR: 00021002 <CE,ME>  CR: 42044022  XER: 20000000
DEAR: bffe4008 ESR: 00000000 
GPR00: c16d1860 c192df90 c18f2340 c16eec58 00000000 00000000 05000000 00000000 
GPR08: 00000000 bffe4000 00000000 bc000000 00000000 0570ad40 ffffffff 7ffb0aec 
GPR16: 00000000 00000000 7fe4dd70 00000000 7fe4ddb0 00000000 c192c000 00000007 
GPR24: 00000000 c1940000 c16eec58 00000000 ffffffff 03fe4000 00000000 c18f0000
NIP [c16ee934] of_scan_flat_dt+0x28/0x148
LR [c16d1860] early_get_first_memblock_info+0x38/0x84
Call Trace:
[c192dfc0] [c16d1860] early_get_first_memblock_info+0x38/0x84
[c192dfd0] [c16d4888] relocate_init+0x98/0x160
[c192dff0] [c100045c] set_ivor+0x144/0x190
Instruction dump:
7c0803a6 4e800020 9421ffd0 7c0802a6 bee1000c 3f20c194 8139a45c 7c7a1b78
90010034 7c9b2378 3b80ffff 3ae00007 <83e90008> 3b00fff8 7fe9fa14 48000008
---[ end trace 41ed10ed80b8d831 ]---
Kernel panic - not syncing: Attempted to kill the idle task!

quoted

diff --git a/arch/powerpc/mm/fsl_booke_mmu.c b/arch/powerpc/mm/fsl_booke_mmu.c
index 048d716ae706..ce0c7d7db6c3 100644
--- a/arch/powerpc/mm/fsl_booke_mmu.c
+++ b/arch/powerpc/mm/fsl_booke_mmu.c

@@ -171,11 +171,10 @@ unsigned long calc_cam_sz(unsigned long ram, unsigned long virt,
 	return 1UL << camsize;
 }
 
-unsigned long map_mem_in_cams(unsigned long ram, int max_cam_idx)
+static unsigned long map_mem_in_cams_addr(phys_addr_t phys, unsigned long virt,
+					unsigned long ram, int max_cam_idx)
 {
 	int i;
-	unsigned long virt = PAGE_OFFSET;
-	phys_addr_t phys = memstart_addr;
 	unsigned long amount_mapped = 0;
 
 	/* Calculate CAM values */

@@ -195,6 +194,14 @@ unsigned long map_mem_in_cams(unsigned long ram, int max_cam_idx)
 	return amount_mapped;
 }
 
+unsigned long map_mem_in_cams(unsigned long ram, int max_cam_idx)
+{
+	unsigned long virt = PAGE_OFFSET;
+	phys_addr_t phys = memstart_addr;
+
+	return map_mem_in_cams_addr(phys, virt, ram, max_cam_idx);
+}
+
 #ifdef CONFIG_PPC32
 
 #if defined(CONFIG_LOWMEM_CAM_NUM_BOOL) && (CONFIG_LOWMEM_CAM_NUM >= NUM_TLBCAMS)

@@ -289,7 +296,11 @@ notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)
 		is_second_reloc = 1;
 		n = switch_to_as1();
 		/* map a 64M area for the second relocation */
-		map_mem_in_cams(0x4000000UL, CONFIG_LOWMEM_CAM_NUM);
+		if (memstart_addr > start)
+			map_mem_in_cams(0x4000000, CONFIG_LOWMEM_CAM_NUM);
+		else
+			map_mem_in_cams_addr(start, PAGE_OFFSET - offset,
+					0x4000000, CONFIG_LOWMEM_CAM_NUM);
 		restore_to_as0(n, offset, __va(dt_ptr));
 		/* We should never reach here */
 		panic("Relocation error");

I'm having a hard time following the logic here.  What is PAGE_OFFSET -
offset supposed to be?  Why would we map anything belowe PAGE_OFFSET?

No, we don't map the address below PAGE_OFFSET.
    memstart_addr is the physical start address of RAM.
    start is the kernel running physical address aligned with 64M.

    offset = memstart_addr - start

So if memstart_addr < start, the offset is negative. The PAGE_OFFSET - offset
is the virtual start address we should use for the init 64M map. It's above
the PAGE_OFFSET instead of below.

For example, if we boot the kernel at 0x5000000:
    memstart_addr = 0x0
    start = 0x4000000
    offset = -0x4000000
    PAGE_OFFSET - offset = 0xc4000000.

Then we should create a 64M map for the virtual address from
0xc4000000 ~ 0xc8000000. This is the final virtual address that the kernel
symbols would use.

Thanks,
Kevin

-Scott