lkml.org 
[lkml]   [2012]   [May]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [tip:x86/platform] vsmp: Fix number of CPUs when vsmp is disabled
Hi Ingo,

On Tue, May 08, 2012 at 02:25:49PM +0200, Ingo Molnar wrote:
>
> On !CONFIG_SMP this produces the following build failure:
>
> arch/x86/kernel/vsmp_64.c:171:6: error: ‘setup_max_cpus’ undeclared (first use in this function)
>
> Do you want to keep vSMP on UP? If not then you could add a
> 'depends on SMP' to the vSMP Kconfig entry, avoiding the whole
> UP problem space.

Oops, sorry for that.

vsmp_64.c is built even if CONFIG_X86_VSMP is not set, so even if we set
this dependency, it will not fix this issue.
How about the following CONFIG_SMP check instead?

Thanks,
Ido.

From b3c6d985b101364dd74f0efaf42c6b34fc7615f9 Mon Sep 17 00:00:00 2001
From: Shai Fultheim <shai@scalemp.com>
Date: Mon, 16 Apr 2012 10:39:35 +0300
Subject: [PATCH] vsmp: Fix number of CPUs when vsmp is disabled

In case CONFIG_X86_VSMP is not set, limit the number of CPUs to the
number of CPUs of the first board.

Signed-off-by: Shai Fultheim <shai@scalemp.com>
[ido@wizery.com: rebased, fixed minor coding-style issues]
Signed-off-by: Ido Yariv <ido@wizery.com>
---
arch/x86/kernel/vsmp_64.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 files changed, 43 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index a1d804b..06779b7 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/arch/x86/kernel/vsmp_64.c
@@ -15,6 +15,7 @@
#include <linux/init.h>
#include <linux/pci_ids.h>
#include <linux/pci_regs.h>
+#include <linux/smp.h>

#include <asm/apic.h>
#include <asm/pci-direct.h>
@@ -22,6 +23,8 @@
#include <asm/paravirt.h>
#include <asm/setup.h>

+#define TOPOLOGY_REGISTER_OFFSET 0x10
+
#if defined CONFIG_PCI && defined CONFIG_PARAVIRT
/*
* Interrupt control on vSMPowered systems:
@@ -149,12 +152,52 @@ int is_vsmp_box(void)
return 0;
}
#endif
+
+static void __init vsmp_cap_cpus(void)
+{
+ void __iomem *address;
+ unsigned int cfg, topology, node_shift, maxcpus;
+
+#ifdef CONFIG_X86_VSMP
+ /* VSMP is enabled, no need to cap cpus */
+ return;
+#elif CONFIG_SMP
+ /*
+ * CONFIG_X86_VSMP is not configured, so limit the number CPUs to the
+ * ones present in the first board, unless explicitly overridden by
+ * setup_max_cpus
+ */
+ if (setup_max_cpus != NR_CPUS)
+ return;
+
+ /* Read the vSMP Foundation topology register */
+ cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0);
+ address = early_ioremap(cfg + TOPOLOGY_REGISTER_OFFSET, 4);
+ if (WARN_ON(!address))
+ return;
+
+ topology = readl(address);
+ node_shift = (topology >> 16) & 0x7;
+ if (!node_shift)
+ /* The value 0 should be decoded as 8 */
+ node_shift = 8;
+ maxcpus = (topology & ((1 << node_shift) - 1)) + 1;
+
+ pr_info("vSMP CTL: Capping CPUs to %d (CONFIG_X86_VSMP is unset)\n",
+ maxcpus);
+ setup_max_cpus = maxcpus;
+ early_iounmap(address, 4);
+#endif
+}
+
void __init vsmp_init(void)
{
detect_vsmp_box();
if (!is_vsmp_box())
return;

+ vsmp_cap_cpus();
+
set_vsmp_pv_ops();
return;
}
--
1.7.6.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2012-05-09 10:41    [from the cache]
©2003-2011 Jasper Spaans