linux-kernel - Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 24 Feb 2008 13:29:03 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Yinghai Lu <Yinghai.Lu@....COM>
Cc:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	kiran@...lemp.com, shai@...lemp.com
Subject: Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2

On Sat, Feb 23, 2008 at 09:48:42PM -0800, Yinghai Lu wrote:
> 
> quad core 8 socket system will have apic id lifting.the apic id range could
> be [4, 0x23]. and apic_is_clustered_box will think that need to three clusters
> and that is large than 2. So it is treated as clustered_box.

Ok I see you chose the quick hack over doing it properly ...

> 
> and will get
> 
> Marking TSC unstable due to TSCs unsynchronized
> 
> even the CPUs have X86_FEATURE_CONSTANT_TSC set.

I doubt that will do the right thing on AMD based vSMP,
which also required the cluster check on AMD iirc.

Cc'ed Kiran/Shai. damage has already hit x86 tree I believe.

-Andi

diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index d8d03e0..7d8ffda 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -1180,9 +1180,19 @@ __cpuinit int apic_is_clustered_box(void)
 {
        int i, clusters, zeros;
        unsigned id;
-       u16 *bios_cpu_apicid = x86_bios_cpu_apicid_early_ptr;
+       u16 *bios_cpu_apicid;
        DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
+       /*
+        * Some AMD box with quadcore cpu and 8 sockets apicid
+        * will be [4, 0x23] or [8, 0x27] could be thought to
+        * have three apic_clusters. So go out early.
+        */
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+               return 0;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/