)]}'
{
  "commit": "b239fb2501117bf3aeb4dd6926edd855be92333d",
  "tree": "62ac25204632ef0b14e3bd84580c722e69800cf7",
  "parents": [
    "3dc494e86d1c93afd4c66385f270899dbfae483d"
  ],
  "author": {
    "name": "Jeremy Fitzhardinge",
    "email": "jeremy@goop.org",
    "time": "Wed May 02 19:27:13 2007 +0200"
  },
  "committer": {
    "name": "Andi Kleen",
    "email": "andi@basil.nowhere.org",
    "time": "Wed May 02 19:27:13 2007 +0200"
  },
  "message": "[PATCH] i386: PARAVIRT: Hooks to set up initial pagetable\n\nThis patch introduces paravirt_ops hooks to control how the kernel\u0027s\ninitial pagetable is set up.\n\nIn the case of a native boot, the very early bootstrap code creates a\nsimple non-PAE pagetable to map the kernel and physical memory.  When\nthe VM subsystem is initialized, it creates a proper pagetable which\nrespects the PAE mode, large pages, etc.\n\nWhen booting under a hypervisor, there are many possibilities for what\npaging environment the hypervisor establishes for the guest kernel, so\nthe constructon of the kernel\u0027s pagetable depends on the hypervisor.\n\nIn the case of Xen, the hypervisor boots the kernel with a fully\nconstructed pagetable, which is already using PAE if necessary.  Also,\nXen requires particular care when constructing pagetables to make sure\nall pagetables are always mapped read-only.\n\nIn order to make this easier, kernel\u0027s initial pagetable construction\nhas been changed to only allocate and initialize a pagetable page if\nthere\u0027s no page already present in the pagetable.  This allows the Xen\nparavirt backend to make a copy of the hypervisor-provided pagetable,\nallowing the kernel to establish any more mappings it needs while\nkeeping the existing ones.\n\nA slightly subtle point which is worth highlighting here is that Xen\nrequires all kernel mappings to share the same pte_t pages between all\npagetables, so that updating a kernel page\u0027s mapping in one pagetable\nis reflected in all other pagetables.  This makes it possible to\nallocate a page and attach it to a pagetable without having to\nexplicitly enumerate that page\u0027s mapping in all pagetables.\n\nAnd:\n\n+From: \"Eric W. Biederman\" \u003cebiederm@xmission.com\u003e\n\nIf we don\u0027t set the leaf page table entries it is quite possible that\nwill inherit and incorrect page table entry from the initial boot\npage table setup in head.S.  So we need to redo the effort here,\nso we pick up PSE, PGE and the like.\n\nHypervisors like Xen require that their page tables be read-only,\nwhich is slightly incompatible with our low identity mappings, however\nI discussed this with Jeremy he has modified the Xen early set_pte\nfunction to avoid problems in this area.\n\nSigned-off-by: Eric W. Biederman \u003cebiederm@xmission.com\u003e\nSigned-off-by: Jeremy Fitzhardinge \u003cjeremy@xensource.com\u003e\nSigned-off-by: Andi Kleen \u003cak@suse.de\u003e\nAcked-by: William Irwin \u003cbill.irwin@oracle.com\u003e\nCc: Ingo Molnar \u003cmingo@elte.hu\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "cba7a15ce1b00016f702af326809b77dc0c0c5c4",
      "old_mode": 33188,
      "old_path": "arch/i386/kernel/paravirt.c",
      "new_id": "47d075bdfb95cc1a85ae415d99079880db24ccee",
      "new_mode": 33188,
      "new_path": "arch/i386/kernel/paravirt.c"
    },
    {
      "type": "modify",
      "old_id": "bd5ef37185044bb0526a96628010830888ab4c6e",
      "old_mode": 33188,
      "old_path": "arch/i386/mm/init.c",
      "new_id": "e8545dcf06c559991e8a52309ccc3c6d0851339d",
      "new_mode": 33188,
      "new_path": "arch/i386/mm/init.c"
    },
    {
      "type": "modify",
      "old_id": "0aacb13bb9295ba95ea2ce831fd739063bcd66e0",
      "old_mode": 33188,
      "old_path": "include/asm-i386/paravirt.h",
      "new_id": "c49b44cdd8ee222ca9db46587ae3d27ce58551ea",
      "new_mode": 33188,
      "new_path": "include/asm-i386/paravirt.h"
    },
    {
      "type": "modify",
      "old_id": "147f2553784d6f8907a970424ad71ee0e53ef070",
      "old_mode": 33188,
      "old_path": "include/asm-i386/pgtable.h",
      "new_id": "0790ad6ed4404e499bd831e749b9ece0be3bcb3f",
      "new_mode": 33188,
      "new_path": "include/asm-i386/pgtable.h"
    }
  ]
}