Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ce22e1d39429c7de9f054ce8d03278dd2010b642
Commit:     ce22e1d39429c7de9f054ce8d03278dd2010b642
Parent:     488b5ec871191359b9b79262a3d48456dae7ea5f
Author:     David S. Miller <[EMAIL PROTECTED]>
AuthorDate: Thu Feb 7 02:14:48 2008 -0800
Committer:  David S. Miller <[EMAIL PROTECTED]>
CommitDate: Thu Feb 7 02:58:40 2008 -0800

    [SPARC64]: Fix booting on non-zero cpu.
    
    The early per-cpu handling needs a slight tweak to work when booting
    on a non-zero cpu.
    
    We got away with this for a long time, but can't any longer as now
    even printk() calls functions (cpu_clock() for example) that thus make
    early references to per-cpu variables.
    
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
 arch/sparc64/kernel/head.S |   25 +++++++++++++++++++++++++
 arch/sparc64/prom/init.c   |    3 +++
 2 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/arch/sparc64/kernel/head.S b/arch/sparc64/kernel/head.S
index c4147ad..44b105c 100644
--- a/arch/sparc64/kernel/head.S
+++ b/arch/sparc64/kernel/head.S
@@ -632,11 +632,36 @@ tlb_fixup_done:
        /* Not reached... */
 
 1:
+       /* If we boot on a non-zero cpu, all of the per-cpu
+        * variable references we make before setting up the
+        * per-cpu areas will use a bogus offset.  Put a
+        * compensating factor into __per_cpu_base to handle
+        * this cleanly.
+        *
+        * What the per-cpu code calculates is:
+        *
+        *      __per_cpu_base + (cpu << __per_cpu_shift)
+        *
+        * These two variables are zero initially, so to
+        * make it all cancel out to zero we need to put
+        * "0 - (cpu << 0)" into __per_cpu_base so that the
+        * above formula evaluates to zero.
+        *
+        * We cannot even perform a printk() until this stuff
+        * is setup as that calls cpu_clock() which uses
+        * per-cpu variables.
+        */
+       sub     %g0, %o0, %o1
+       sethi   %hi(__per_cpu_base), %o2
+       stx     %o1, [%o2 + %lo(__per_cpu_base)]
 #else
        mov     0, %o0
 #endif
        sth     %o0, [%g6 + TI_CPU]
 
+       call    prom_init_report
+        nop
+
        /* Off we go.... */
        call    start_kernel
         nop
diff --git a/arch/sparc64/prom/init.c b/arch/sparc64/prom/init.c
index 1c0db84..87e7c7e 100644
--- a/arch/sparc64/prom/init.c
+++ b/arch/sparc64/prom/init.c
@@ -48,7 +48,10 @@ void __init prom_init(void *cif_handler, void *cif_stack)
        prom_getstring(node, "version", prom_version, sizeof(prom_version));
 
        prom_printf("\n");
+}
 
+void __init prom_init_report(void)
+{
        printk("PROMLIB: Sun IEEE Boot Prom '%s'\n", prom_version);
        printk("PROMLIB: Root node compatible: %s\n", prom_root_compatible);
 }
-
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