• Ingo Molnar's avatar
    x86/boot/e820: Rename early_reserve_e820() to e820__memblock_alloc() and document it · 5da217ca
    Ingo Molnar authored
    early_reserve_e820() is an early hack for kexec that does a limited fixup of the
    mptable and passes it to the kexec kernel as if it was the real thing.
    
    For this it needs to allocate memory - but no memory allocator is available yet
    beyond the memblock allocator, so early_reserve_e820() is really a wrapper
    around memblock_alloc() plus a hack to update the e820_table_firmware entries.
    
    The name 'reserve' is really a bit of a misnomer, as 'reserved' memory typically
    means memory completely inaccessible to the kernel - while here what we want to do
    is a special RAM allocation for our own purposes and insert that as RAM_RESERVED.
    
    Rename the function to e820__memblock_alloc_reserved() to better signal this dual
    purpose, plus document it better, which was omitted when it was merged. The barely
    comprehensible and cryptic comment:
    
      /*
       * pre allocated 4k and reserved it in memblock and e820_table_firmware
       */
      u64 __init e820__memblock_alloc_reserved(u64 size, u64 align)
    
    ... does not count as documentation, replace it with:
    
      /*
       * Allocate the requested number of bytes with the requsted alignment
       * and return (the physical address) to the caller. Also register this
       * range in the 'firmware' E820 table.
       *
       * This allows kexec to fake a new mptable, as if it came from the real
       * system.
       */
      u64 __init e820__memblock_alloc_reserved(u64 size, u64 align)
    
    No change in functionality.
    
    Cc: Alex Thorlton <athorlton@sgi.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Huang, Ying <ying.huang@intel.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Paul Jackson <pj@sgi.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rafael J. Wysocki <rjw@sisk.pl>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Wei Yang <richard.weiyang@gmail.com>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    5da217ca
mpparse.c 21.1 KB