All of lore.kernel.org
 help / color / mirror / Atom feed
* [DOCS/PATCH] http://wiki.xen.org/wiki/X86_Paravirtualised_Memory_Management changes
@ 2013-01-28 18:32 Konrad Rzeszutek Wilk
  2013-01-28 18:32 ` [PATCH 1/8] docs: Document the ELF notes Konrad Rzeszutek Wilk
                   ` (8 more replies)
  0 siblings, 9 replies; 21+ messages in thread
From: Konrad Rzeszutek Wilk @ 2013-01-28 18:32 UTC (permalink / raw)
  To: xen-devel

These changes would allow the above mention Wiki to reference to
more materials. This is what I had in mind to add to the Wiki:

diff --git a/intro.txt b/intro.txt
index b902b1e..72d3ca1 100644
--- a/intro.txt
+++ b/intro.txt
@@ -339,6 +339,188 @@ into the page table base register but will not be explicitly pinned.
 The initial virtual and pseudo-physical layout of a new guest is
 described [http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday here].
 
+
+At the start of the guest, the kernel image is read and the ELF section is
+parsed. The hypervisor looks a specific section that has the string ‘Xen’
+(or “xen”) to find out: where the kernel expects its virtual base address,
+what type of hypervisor it can work with, certain features the kernel image
+can support, and the location of the hypercall. There are two variants of this:
+
+; a). The lagacy ASCIIZ string with all of the keys concatenated. Each key
+being a string and the equal sign with the value also being an string
+(numeric values are typed as string). The delimiter is a comma.
+The key can be up to 32 characters and the value up to 128 characters.
+For example:
+
+	GUEST_OS=Mini-OS,XEN_VER=xen-3.0,VIRT_BASE=0x0,ELF_PADDR_OFFSET=0x0,HYPERCALL_PAGE=0x2,LOADER=generic
+
+; b). A “.note.Xen” section in ELF header conforming to the ELF .note” format.
+This structure is a 4-byte aligned structure. First section is an numerical
+key (aligned to 4 bytes); followed by either a string or a numerical value
+(again, aligned to 4 bytes). The values can up to any length, if the key is
+assumed to a string. If it is a numerical value, it is a long
+(64-bit value - which means 8 bytes).
+
+The parameters and its purpose are explained in
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,elfnote.h.html#incontents_elfnote here].
+
+And the XEN_ELF_FEATURES values are explained in
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,features.h.html#incontents_elfnote_features here].
+
+For example, if the ELF values were as so:
+
+{| border="1" cellpadding="2" cellspacing="0"
+ | Name of Xen ELF entry
+ | Contents
+ |-
+ | XEN_ELFNOTE_GUEST_OS (6)
+ | linux
+ |-
+ | XEN_ELFNOTE_GUEST_VERSION (7)
+ | 2.6
+ |-
+ | XEN_ELFNOTE_XEN_VERSION (5)
+ | xen-3.0
+ |-
+ | XEN_ELFNOTE_VIRT_BASE (3)
+ | 0xffffffff80000000
+ |-
+ | XEN_ELFNOTE_ENTRY (1)
+ | 0xffffffff81899200
+ |-
+ | XEN_ELFNOTE_HYPERCALL_PAGE (2)
+ | 0xffffffff81001000
+ |-
+ | XEN_ELFNOTE_FEATURES (10)
+ | !writable_page_tables|pae_pgdir_above_4gb
+ |-
+ | XEN_ELFNOTE_PAE_MODE (9)
+ | yes
+ |-
+ | XEN_ELFNOTE_LOADER (8)
+ | generic
+ |-
+ | XEN_ELFNOTE_SUSPEND_CANCEL (14)
+ | 1
+ |-
+ | XEN_ELFNOTE_HV_START_LOW
+ | 0xffff800000000000
+ |-
+ | XEN_ELFNOTE_PADDR_OFFSET
+ | 0
+ |}
+
+With that setup, the hypervisor constructs an initial page table that spans the
+region from virtual start address up (0xffffffff80000000) to the end of the
+p2m map.
+
+For example, the layout (which then is going to be feed in
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday]
+can look as so:
+
+{| border="1" cellpadding="2" cellspacing="0"
+ | Page Frame (PFN)
+ | contents
+ |-
+ | 0x0
+ | location of [http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday_shared struct shared_info]
+ |-
+ | 0x1000
+ | location of the kernel
+ |-
+ | 0x1001
+ | location of the hypercall within the kernel
+ |-
+ | 0x1E3E
+ | ramdisk
+ |-
+ | 0xFC69
+ | phys2mach (P2M) - an array of machine frame numbers. The total size of this array is dependent on the nr_pages in
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday struct start_info]
+and the architecture of the guest (each entry is four bytes
+under 32-bit kernels and eight bytes under 64-bit kernels).
+ |-
+ | 0xFCE9
+ | location of 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday start_info structure]
+ |-
+ | 0xFCEA
+ | location of
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,io,xs_wire.h.html#incontents_xenstore_struct XenStore structure].
+Also refer to XXX docs/misc/xenstore.txt
+ |-
+ | 0xFCEB
+ | Depending on the type of the guest (initial domain or subsequent domains), it can either be the
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday_dom0_console dom0_vga_console_info structure]
+or 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,io,console.h.html XenConsole structure].
+The parameters defining this location are in the 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday start_info structure]
+ |-
+ | 0xFCEC
+ | bootstrap page tables. These pagetables are loaded in the guest at startup
+and cover from 0x0 up to 0xFD6f (the bootstack).
+ |-
+ | 0xFD6F
+ | bootstrap stack.
+ |}
+
+In terms of virtual addresses, these example PFNs are mapped to virtual addresses
+as follow:
+{| border="1" cellpadding="2" cellspacing="0"
+ | Virtual Address
+ | contents
+ |-
+ | 0xffffffff80000000
+ | location of [http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday_shared struct shared_info]
+ |-
+ | 0xffffffff81000000
+ | location of the kernel
+ |-
+ | 0xffffffff81001000
+ | location of the hypercall within the kernel
+ |-
+ | 0xffffffff81e3e000 
+ | ramdisk
+ |-
+ | 0xffffffff8fc69000
+ | phys2mach (P2M) - an array of machine frame numbers. The total size of this array is dependent on the nr_pages in
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday struct start_info]
+and the architecture of the guest (each entry is four bytes
+under 32-bit kernels and eight bytes under 64-bit kernels).
+ |-
+ | 0xffffffff8fce9000
+ | location of 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday start_info structure]
+ |-
+ | 0xffffffff8fcea000
+ | location of
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,io,xs_wire.h.html#incontents_xenstore_struct XenStore structure].
+Also refer to XXX docs/misc/xenstore.txt
+ |-
+ | 0xffffffff8fceb000
+ | Depending on the type of the guest (initial domain or subsequent domains), it can either be the
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday_dom0_console dom0_vga_console_info structure]
+or 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,io,console.h.html XenConsole structure].
+The parameters defining this location are in the 
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday start_info structure]
+ |-
+ | 0xffffffff8fcfc000
+ | bootstrap page tables. These pagetables are loaded in the guest at startup
+and cover from 0x0 up to 0xFD6f (the bootstack).
+ |-
+ | 0xffffffff8fd6f000
+ | bootstrap stack.
+ |}
+
+When the guest is launched, per
+[http://xenbits.xen.org/docs/unstable/hypercall/include,public,xen.h.html#incontents_startofday]
+explanation, the register %esi contains the virtual address to the
+start_info_t (0xffffffff8fce9000), the %cr3 points to the beginning of the
+bootstrap page-tables (0xffffffff8fcfc000), and the %esp points to the
+bootstrap stack (0xffffffff8fd6f000).
+
 = Virtual Address Space =
 
 Xen enforces certain restrictions on the virtual addresses which are


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

^ permalink raw reply related	[flat|nested] 21+ messages in thread
end of thread, other threads:[~2013-01-31  9:58 UTC | newest]

Thread overview: 21+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-01-28 18:32 [DOCS/PATCH] http://wiki.xen.org/wiki/X86_Paravirtualised_Memory_Management changes Konrad Rzeszutek Wilk
2013-01-28 18:32 ` [PATCH 1/8] docs: Document the ELF notes Konrad Rzeszutek Wilk
2013-01-29  9:16   ` Ian Campbell
2013-01-28 18:32 ` [PATCH 2/8] docs: Provide some examples of the various ELF values Konrad Rzeszutek Wilk
2013-01-29  9:23   ` Ian Campbell
2013-01-28 18:32 ` [PATCH 3/8] docs: Document the ELF_FEATURES entry Konrad Rzeszutek Wilk
2013-01-29  9:23   ` Ian Campbell
2013-01-28 18:32 ` [PATCH 4/8] docs: Add some extra details to the ELF note Konrad Rzeszutek Wilk
2013-01-29  9:26   ` Ian Campbell
2013-01-28 18:32 ` [PATCH 5/8] docs: Document the shared structure Konrad Rzeszutek Wilk
2013-01-29  9:26   ` Ian Campbell
2013-01-28 18:32 ` [PATCH 6/8] docs: Document the dom0_vga_console_info structure Konrad Rzeszutek Wilk
2013-01-29  9:31   ` Ian Campbell
2013-01-30 17:10     ` Konrad Rzeszutek Wilk
2013-01-28 18:32 ` [PATCH 7/8] docs: Document start_info changes in Xen 4.2 Konrad Rzeszutek Wilk
2013-01-29  9:37   ` Ian Campbell
2013-01-30 17:23     ` Konrad Rzeszutek Wilk
2013-01-31  9:58       ` Ian Campbell
2013-01-28 18:32 ` [PATCH 8/8] docs: Document the XenBus structure Konrad Rzeszutek Wilk
2013-01-29  9:38   ` Ian Campbell
2013-01-29 10:05 ` [DOCS/PATCH] http://wiki.xen.org/wiki/X86_Paravirtualised_Memory_Management changes Ian Campbell

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.