From: Andrew Morton <akpm@osdl.org>
To: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org,
jun.nakajima@intel.com, "Martin J. Bligh" <mbligh@aracnet.com>,
"Brown, Len" <len.brown@intel.com>
Subject: Re: [PATCH] bug in bigsmp CPU bringup
Date: Wed, 5 May 2004 19:03:32 -0700 [thread overview]
Message-ID: <20040505190332.395cac70.akpm@osdl.org> (raw)
In-Reply-To: <88056F38E9E48644A0F562A38C64FB6001BFF5A9@scsmsx403.sc.intel.com>
Len, Martin: please review?
From: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
There is an bug in bigsmp sub-architecture, due to which it will not enable
all the CPUs when the BIOS-APICIDs are not 0 to n-1 (where n is total
number of CPUs). Particularly, only 2 CPU comes up on a system that has 4
CPUs with BIOS APICID as (0, 1, 6, 7).
The bug is root caused to check_apicid_present(bit) call in smpboot.c, when
bigsmp is expecting apicid in place of bit. check_apicid_present(bit) in
bigsmp subarchitecture checks the bit with phys_id_present_map (which is
actually map representing all apicids and not bit).
One solution is to change check_apicid_present(bit) to
check_apicid_present(apicid), in smp_boot_cpus(). But, it can affect all
the other subarchitectures in various subtle ways. So, here is a simple
alternate fix (Thanks to Martin Bligh), which solves the above problem.
---
25-akpm/include/asm-i386/mach-bigsmp/mach_apic.h | 3 ++-
1 files changed, 2 insertions(+), 1 deletion(-)
diff -puN include/asm-i386/mach-bigsmp/mach_apic.h~bigsmp-cpu-bringup-fix include/asm-i386/mach-bigsmp/mach_apic.h
--- 25/include/asm-i386/mach-bigsmp/mach_apic.h~bigsmp-cpu-bringup-fix 2004-05-05 19:02:18.299905696 -0700
+++ 25-akpm/include/asm-i386/mach-bigsmp/mach_apic.h 2004-05-05 19:02:18.302905240 -0700
@@ -37,9 +37,10 @@ static inline unsigned long check_apicid
return 0;
}
+/* we don't use the phys_cpu_present_map to indicate apicid presence */
static inline unsigned long check_apicid_present(int bit)
{
- return physid_isset(bit, phys_cpu_present_map);
+ return 1;
}
#define apicid_cluster(apicid) (apicid & 0xF0)
_
next prev parent reply other threads:[~2004-05-06 2:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-06 1:43 Pallipadi, Venkatesh
2004-05-06 2:03 ` Andrew Morton [this message]
2004-05-06 5:27 ` Martin J. Bligh
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