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Message-ID: <46EE9D66.1030705@zytor.com>
Date: Mon, 17 Sep 2007 08:29:42 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: "Huang, Ying" <ying.huang@...el.com>
CC: Andi Kleen <ak@...e.de>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
akpm@...ux-foundation.org, Yinghai Lu <yhlu.kernel@...il.com>,
Chandramouli Narayanan <mouli@...ux.intel.com>,
linux-kernel@...r.kernel.org
Subject: Re: [RFC -mm 2/2] i386/x86_64 boot: document for 32 bit boot protocol
Huang, Ying wrote:
> This patch defines a 32-bit boot protocol and adds corresponding
> document.
> +
> +In addition to read/modify/write kernel header of the zero page as
> +that of 16-bit boot protocol, the boot loader should fill the
> +following additional fields of the zero page too.
> +
> +Offset Type Description
> +------ ---- -----------
> + 0 32 bytes struct screen_info, SCREEN_INFO
> + ATTENTION, overlaps the following !!!
> + 2 unsigned short EXT_MEM_K, extended memory size in Kb (from int 0x15)
> + 0x20 unsigned short CL_MAGIC, commandline magic number (=0xA33F)
> + 0x22 unsigned short CL_OFFSET, commandline offset
> + Address of commandline is calculated:
> + 0x90000 + contents of CL_OFFSET
> + (only taken, when CL_MAGIC = 0xA33F)
> + 0x40 20 bytes struct apm_bios_info, APM_BIOS_INFO
> + 0x60 16 bytes Intel SpeedStep (IST) BIOS support information
> + 0x80 16 bytes hd0-disk-parameter from intvector 0x41
> + 0x90 16 bytes hd1-disk-parameter from intvector 0x46
> +
> + 0xa0 16 bytes System description table truncated to 16 bytes.
> + ( struct sys_desc_table_struct )
> + 0xb0 - 0x13f Free. Add more parameters here if you really need them.
> + 0x140- 0x1be EDID_INFO Video mode setup
> +
> +0x1c4 unsigned long EFI system table pointer
> +0x1c8 unsigned long EFI memory descriptor size
> +0x1cc unsigned long EFI memory descriptor version
> +0x1d0 unsigned long EFI memory descriptor map pointer
> +0x1d4 unsigned long EFI memory descriptor map size
> +0x1e0 unsigned long ALT_MEM_K, alternative mem check, in Kb
> +0x1e4 unsigned long Scratch field for the kernel setup code
> +0x1e8 char number of entries in E820MAP (below)
> +0x1e9 unsigned char number of entries in EDDBUF (below)
> +0x1ea unsigned char number of entries in EDD_MBR_SIG_BUFFER (below)
> +0x290 - 0x2cf EDD_MBR_SIG_BUFFER (edd.S)
> +0x2d0 - 0xd00 E820MAP
> +0xd00 - 0xeff EDDBUF (edd.S) for disk signature read sector
> +0xd00 - 0xeeb EDDBUF (edd.S) for edd data
> +
> +After loading and setuping the zero page, the boot loader can load the
> +32/64-bit kernel in the same way as that of 16-bit boot protocol.
> +
> +In 32-bit boot protocol, the kernel is started by jumping to the
> +32-bit kernel entry point, which is the start address of loaded
> +32/64-bit kernel.
> +
> +At entry, the CPU must be in 32-bit protected mode with paging
> +disabled; the CS and DS must be 4G flat segments; %esi holds the base
> +address of the "zero page"; %esp, %ebp, %edi should be zero.
This is just replicating the "zero-page.txt" document, which can best be
described as a "total lie" -- compare with the actual structure.
-hpa
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