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From: Yinghai Lu <yinghai@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jan Kiszka <jan.kiszka@web.de>,
	Jason Wessel <jason.wessel@windriver.com>,
	Borislav Petkov <bp@alien8.de>,
	linux-kernel@vger.kernel.org, Yinghai Lu <yinghai@kernel.org>,
	Rob Landley <rob@landley.net>,
	Matt Fleming <matt.fleming@intel.com>
Subject: [PATCH 26/35] x86, boot: Update comments about entries for 64bit image
Date: Thu, 24 Jan 2013 12:20:07 -0800	[thread overview]
Message-ID: <1359058816-7615-27-git-send-email-yinghai@kernel.org> (raw)
In-Reply-To: <1359058816-7615-1-git-send-email-yinghai@kernel.org>

Now 64bit entry is fixed on 0x200, can not be changed anymore.

Update the comments to reflect that.

Also put info about it in boot.txt

-v2: fix some grammar error

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Rob Landley <rob@landley.net>
Cc: Matt Fleming <matt.fleming@intel.com>
---
 Documentation/x86/boot.txt         |   38 ++++++++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/head_64.S |   22 ++++++++++++---------
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index ca96344..8eb78f4 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -1042,6 +1042,44 @@ must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
 must be __BOOT_DS; interrupt must be disabled; %esi must hold the base
 address of the struct boot_params; %ebp, %edi and %ebx must be zero.
 
+**** 64-bit BOOT PROTOCOL
+
+For machine with 64bit cpus and 64bit kernel, we could use 64bit bootloader
+and we need a 64-bit boot protocol.
+
+In 64-bit boot protocol, the first step in loading a Linux kernel
+should be to setup the boot parameters (struct boot_params,
+traditionally known as "zero page"). The memory for struct boot_params
+could be allocated anywhere (even above 4G) and initialized to all zero.
+Then, the setup header at offset 0x01f1 of kernel image on should be
+loaded into struct boot_params and examined. The end of setup header
+can be calculated as follows:
+
+	0x0202 + byte value at offset 0x0201
+
+In addition to read/modify/write the setup header of the struct
+boot_params as that of 16-bit boot protocol, the boot loader should
+also fill the additional fields of the struct boot_params as described
+in zero-page.txt.
+
+After setting up the struct boot_params, the boot loader can load
+64-bit kernel in the same way as that of 16-bit boot protocol, but
+kernel could be loaded above 4G.
+
+In 64-bit boot protocol, the kernel is started by jumping to the
+64-bit kernel entry point, which is the start address of loaded
+64-bit kernel plus 0x200.
+
+At entry, the CPU must be in 64-bit mode with paging enabled.
+The range with setup_header.init_size from start address of loaded
+kernel and zero page and command line buffer get ident mapping;
+a GDT must be loaded with the descriptors for selectors
+__BOOT_CS(0x10) and __BOOT_DS(0x18); both descriptors must be 4G flat
+segment; __BOOT_CS must have execute/read permission, and __BOOT_DS
+must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
+must be __BOOT_DS; interrupt must be disabled; %rsi must hold the base
+address of the struct boot_params.
+
 **** EFI HANDOVER PROTOCOL
 
 This protocol allows boot loaders to defer initialisation to the EFI
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 5c80b94..d9ae9a4 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -37,6 +37,12 @@
 	__HEAD
 	.code32
 ENTRY(startup_32)
+	/*
+	 * 32bit entry is 0 and it is ABI so immutable!
+	 * If we come here directly from a bootloader,
+	 * kernel(text+data+bss+brk) ramdisk, zero_page, command line
+	 * all need to be under the 4G limit.
+	 */
 	cld
 	/*
 	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
@@ -182,20 +188,18 @@ ENTRY(startup_32)
 	lret
 ENDPROC(startup_32)
 
-	/*
-	 * Be careful here startup_64 needs to be at a predictable
-	 * address so I can export it in an ELF header.  Bootloaders
-	 * should look at the ELF header to find this address, as
-	 * it may change in the future.
-	 */
 	.code64
 	.org 0x200
 ENTRY(startup_64)
 	/*
+	 * 64bit entry is 0x200 and it is ABI so immutable!
 	 * We come here either from startup_32 or directly from a
-	 * 64bit bootloader.  If we come here from a bootloader we depend on
-	 * an identity mapped page table being provied that maps our
-	 * entire text+data+bss and hopefully all of memory.
+	 * 64bit bootloader.
+	 * If we come here from a bootloader, kernel(text+data+bss+brk),
+	 * ramdisk, zero_page, command line could be above 4G.
+	 * We depend on an identity mapped page table being provided
+	 * that maps our entire kernel(text+data+bss+brk), zero page
+	 * and command line.
 	 */
 #ifdef CONFIG_EFI_STUB
 	/*
-- 
1.7.10.4


  parent reply	other threads:[~2013-01-24 20:22 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-24 20:19 [PATCH 00/35] x86, boot, 64bit: Add support for loading ramdisk and bzImage above 4G Yinghai Lu
2013-01-24 20:19 ` [PATCH 01/35] x86, mm: Fix page table early allocation offset checking Yinghai Lu
2013-01-30  1:20   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 02/35] x86: Handle multiple exactmaps and out of order exactmap Yinghai Lu
2013-01-24 20:19 ` [PATCH 03/35] x86, mm: Introduce memmap=reserveram Yinghai Lu
2013-01-24 20:19 ` [PATCH 04/35] x86: Clean up e820 add kernel range Yinghai Lu
2013-01-24 23:21   ` Jacob Shin
2013-01-30  1:21   ` [tip:x86/mm2] x86: Factor out e820_add_kernel_range() tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 05/35] x86, 64bit, mm: Make pgd next calculation consistent with pud/pmd Yinghai Lu
2013-01-30  1:22   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 06/35] x86, realmode: Set real_mode permissions early Yinghai Lu
2013-01-30  1:23   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 07/35] x86, 64bit, mm: Add generic kernel/ident mapping helper Yinghai Lu
2013-01-30  1:24   ` [tip:x86/mm2] x86, 64bit, mm: Add generic kernel/ ident " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 08/35] x86, 64bit: Copy zero-page early Yinghai Lu
2013-01-30  1:25   ` [tip:x86/mm2] x86, 64bit: Copy struct boot_params early tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 09/35] x86, 64bit, realmode: Use init_level4_pgt to set trapmoline_pgd directly Yinghai Lu
2013-01-30  1:27   ` [tip:x86/mm2] x86, 64bit, realmode: Use init_level4_pgt to set trampoline_pgd directly tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 10/35] x86, realmode: Separate real_mode reserve and setup Yinghai Lu
2013-01-30  1:28   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 11/35] x86, 64bit: early #PF handler set page table Yinghai Lu
2013-01-30  1:29   ` [tip:x86/mm2] x86, 64bit: Use a #PF handler to materialize early mappings on demand tip-bot for H. Peter Anvin
2013-01-24 20:19 ` [PATCH 12/35] x86, 64bit: #PF handler set page to cover only 2M per #PF Yinghai Lu
2013-01-30  1:30   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 13/35] x86, 64bit: Don't set max_pfn_mapped wrong value early on native path Yinghai Lu
2013-01-30  1:31   ` [tip:x86/mm2] x86, 64bit: Don' t " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 14/35] x86: Merge early_reserve_initrd for 32bit and 64bit Yinghai Lu
2013-01-30  1:32   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 15/35] x86: Add get_ramdisk_image/size() Yinghai Lu
2013-01-30  1:34   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 16/35] x86, boot: Add get_cmd_line_ptr() Yinghai Lu
2013-01-30  1:35   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 17/35] x86, boot: Move checking of cmd_line_ptr out of common path Yinghai Lu
2013-01-30  1:36   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:19 ` [PATCH 18/35] x86, boot: Pass cmd_line_ptr with unsigned long instead Yinghai Lu
2013-01-30  1:37   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 19/35] x86, boot: Move verify_cpu.S and no_longmode down Yinghai Lu
2013-01-30  1:38   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 20/35] x86, boot: Move lldt/ltr out of 64bit code section Yinghai Lu
2013-01-30  1:39   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 21/35] x86, kexec: Remove 1024G limitation for kexec buffer on 64bit Yinghai Lu
2013-01-30  1:40   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 22/35] x86, kexec: Set ident mapping for kernel that is above max_pfn Yinghai Lu
2013-01-30  1:42   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 23/35] x86, kexec: Replace ident_mapping_init and init_level4_page Yinghai Lu
2013-01-30  1:43   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 24/35] x86, kexec, 64bit: Only set ident mapping for ram Yinghai Lu
2013-01-30  1:44   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 25/35] x86, boot: Add fields to support load bzImage and ramdisk above 4G Yinghai Lu
2013-01-28  0:07   ` [tip:x86/boot] x86, boot: Define the 2.12 bzImage boot protocol tip-bot for H. Peter Anvin
2013-01-29  9:48   ` [tip:x86/boot] x86, boot: Sanitize boot_params if not zeroed on creation tip-bot for H. Peter Anvin
2013-01-30  1:45   ` [tip:x86/mm2] x86, boot: enable support load bzImage and ramdisk above 4G tip-bot for Yinghai Lu
2013-01-30  1:54     ` Yinghai Lu
2013-01-30  2:18       ` H. Peter Anvin
2013-01-30  3:47   ` [tip:x86/mm2] x86, boot: Support loading bzImage, boot_params " tip-bot for Yinghai Lu
2013-01-24 20:20 ` Yinghai Lu [this message]
2013-01-30  1:46   ` [tip:x86/mm2] x86, boot: Update comments about entries for 64bit image tip-bot for Yinghai Lu
2013-01-30  3:48   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 27/35] x86, boot: Not need to check setup_header version for setup_data Yinghai Lu
2013-01-30  1:47   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:49   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 28/35] memblock: Add memblock_mem_size() Yinghai Lu
2013-01-30  1:49   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:50   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 29/35] x86, kdump: Remove crashkernel range find limit for 64bit Yinghai Lu
2013-01-30  1:50   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:51   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 30/35] x86: Add Crash kernel low reservation Yinghai Lu
2013-01-30  1:51   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-02-07  5:14     ` Rob Landley
2013-02-07  6:39       ` Yinghai Lu
2013-01-30  3:52   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 31/35] x86: Merge early kernel reserve for 32bit and 64bit Yinghai Lu
2013-01-30  1:52   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:53   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 32/35] x86, 64bit, mm: Mark data/bss/brk to nx Yinghai Lu
2013-01-30  1:53   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:55   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 33/35] x86, 64bit, mm: hibernate use generic mapping_init Yinghai Lu
2013-01-24 22:50   ` Rafael J. Wysocki
2013-01-30  1:54   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:56   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 34/35] mm: Add alloc_bootmem_low_pages_nopanic() Yinghai Lu
2013-01-30  1:56   ` [tip:x86/mm2] " tip-bot for Yinghai Lu
2013-01-30  3:57   ` tip-bot for Yinghai Lu
2013-01-24 20:20 ` [PATCH 35/35] x86: Don't panic if can not alloc buffer for swiotlb Yinghai Lu
2013-01-25 16:47   ` Konrad Rzeszutek Wilk
2013-01-30  1:57   ` [tip:x86/mm2] x86: Don' t " tip-bot for Yinghai Lu
2013-01-30  3:58   ` tip-bot for Yinghai Lu

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