-----Original Message-----
From: ZY - pavel
Sent: Saturday, February 02, 2013 1:24 PM
To: Dinh Nguyen
Cc: Russell King - ARM Linux; olof at lixom.net; linux-arm-
kernel at lists.infradead.org; arnd at arndb.de
Subject: Re: [PATCHv2 for soc 4/4] arm: socfpga: Add SMP support for
actual socfpga harware

Hi!

quoted

quoted

quoted

quoted

I actually thought about that... but could not think of non-

ugly way

quoted

quoted

quoted

quoted

of doing that. I hope dts will normally be "right" for any

production

quoted

quoted

quoted

quoted

system...

I think a panic is better just for the reason that if someone is
expecting SMP, but missed the warning message, and later finds

out that

quoted

quoted

quoted

the secondary core never came up, it would save some debugging

time.

quoted

quoted

quoted

Since I have to send out a v3 from the 1st patch anyways, let me

verify

quoted

quoted

quoted

that I can get the early warning.

The choice is between a panic() at a point where the only way to

find

quoted

quoted

out is to throw in printascii() or a working printk, and ending up

with

quoted

quoted

an unbootable kernel, vs continuing the boot and having an almost
working system which can be logged into and the messages viewed.

If you have an application which relies on the second CPU coming

up,

quoted

quoted

why not have it verify that the second CPU came up (it's quite easy
to do - there's POSIX standard libc calls to get the number of

online

quoted

quoted

CPUs).

Point taken...thanks Russell.

Well, I don't think we normally check dtbs for validity with
user-helpful error messages, but it is relatively easy in this case.

---cut here---

Continue booting with second core disabled if cpu1-start-addr is not
present in .dtb.

Signed-off-by: Pavel Machek <redacted>

diff --git a/arch/arm/mach-socfpga/platsmp.c b/arch/arm/mach-

socfpga/platsmp.c
index 81e0da0..90facdd 100644

--- a/arch/arm/mach-socfpga/platsmp.c
+++ b/arch/arm/mach-socfpga/platsmp.c

@@ -82,6 +82,9 @@ static void __init socfpga_smp_init_cpus(void)
              ncores = 1;
      }
 #endif
+     if (!cpu1start_addr)
+             ncores = 1;
+

      for (i = 0; i < ncores; i++)
              set_cpu_possible(i, true);

diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-

socfpga/socfpga.c
index 334c330..c3cd88b 100644

--- a/arch/arm/mach-socfpga/socfpga.c
+++ b/arch/arm/mach-socfpga/socfpga.c

@@ -74,10 +74,9 @@ static void __init socfpga_sysmgr_init(void)

      np = of_find_compatible_node(NULL, NULL, "altr,sys-mgr");

-     if (of_property_read_u32(np, "cpu1-start-addr", (u32 *)

&cpu1start_addr)) {
-             early_printk("Need cpu1-start-addr in device tree.\n");
-             panic("Need cpu1-start-addr in device tree.\n");
-     }
+     if (of_property_read_u32(np, "cpu1-start-addr", (u32 *)
&cpu1start_addr))
+             printk(KERN_ALERT "Need cpu1-start-addr in device tree for
SMP operation.\n");
+
      sys_manager_base_addr = of_iomap(np, 0);

      np = of_find_compatible_node(NULL, NULL, "altr,rst-mgr");

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html