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SubjectRe: [RFC -mm 2/2] i386/x86_64 boot: document for 32 bit boot protocol
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On Mon, 2007-09-17 at 08:29 -0700, H. Peter Anvin wrote:
> 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.

OK, I will check the actual structure, and change the document
accordingly.

Best Regards,
Huang Ying
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