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  • Tony Luck's avatar
    [IA64] Ensure cpu0 can access per-cpu variables in early boot code · 10617bbe
    Tony Luck authored
    ia64 handles per-cpu variables a litle differently from other architectures
    in that it maps the physical memory allocated for each cpu at a constant
    virtual address (0xffffffffffff0000). This mapping is not enabled until
    the architecture specific cpu_init() function is run, which causes problems
    since some generic code is run before this point. In particular when
    CONFIG_PRINTK_TIME is enabled, the boot cpu will trap on the access to
    per-cpu memory at the first printk() call so the boot will fail without
    the kernel printing anything to the console.
    Fix this by allocating percpu memory for cpu0 in the kernel data section
    and doing all initialization to enable percpu access in head.S before
    calling any generic code.
    Other cpus must take care not to access per-cpu variables too early, but
    their code path from start_secondary() to cpu_init() is all in arch/ia64
    Signed-off-by: default avatarTony Luck <>