lkml.org 
[lkml]   [2012]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high
From
On Wed, Nov 21, 2012 at 9:17 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 11/20/2012 11:16 PM, Yinghai Lu wrote:
>>
>>
>> diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
>> index 9efceff..a8263f7 100644
>> --- a/Documentation/x86/boot.txt
>> +++ b/Documentation/x86/boot.txt
>> @@ -57,6 +57,9 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol
>> for relaxed alignment
>> Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI
>> handover
>> protocol entry point.
>>
>> +Protocol 2.12: (Kernel 3.9) Added three fields for loading bzImage and
>> + ramdisk above 4G with 64bit.
>> +
>> **** MEMORY LAYOUT
>>
>> The traditional memory map for the kernel loader, used for Image or
>> @@ -182,7 +185,7 @@ Offset Proto Name Meaning
>> 0230/4 2.05+ kernel_alignment Physical addr alignment required
>> for kernel
>> 0234/1 2.05+ relocatable_kernel Whether kernel is relocatable
>> or not
>> 0235/1 2.10+ min_alignment Minimum alignment, as a power of
>> two
>> -0236/2 N/A pad3 Unused
>> +0236/2 2.12+ xloadflags Boot protocal option flags
>
> ^^^^^^^^
sorry.
>
>> 0238/4 2.06+ cmdline_size Maximum size of the kernel command
>> line
>> 023C/4 2.07+ hardware_subarch Hardware subarchitecture
>> 0240/8 2.07+ hardware_subarch_data Subarchitecture-specific
>> data
>> @@ -193,6 +196,9 @@ Offset Proto Name Meaning
>> 0258/8 2.10+ pref_address Preferred loading address
>> 0260/4 2.10+ init_size Linear memory required during
>> initialization
>> 0264/4 2.11+ handover_offset Offset of handover entry point
>> +0268/4 2.12+ ext_ramdisk_image ramdisk_image 32 bits
>
>
> "high 32 bits" presumably...

ok

>
>
>> +026C/4 2.12+ ext_ramdisk_size ramdisk_size high 32 bits
>> +0270/4 2.12+ ext_cmd_line_ptr cmd_line_ptr high 32 bits
>
>
> I'm looking at these three fields and I'm getting worried about space --
> there are only two more word-sized fields possible in this structure. Since
> these fields are not initialized (default to zero) and almost certainly
> aren't useful for people entering via the 16-bit entry point I think we
> should move them out of struct setup_header and into the remainder of struct
> boot_param.

in boot_param:

struct setup_header hdr; /* setup header */ /* 0x1f1 */
__u8 _pad7[0x290-0x1f1-sizeof(struct setup_header)];
__u32 edd_mbr_sig_buffer[EDD_MBR_SIG_MAX]; /* 0x290 */
struct e820entry e820_map[E820MAX]; /* 0x2d0 */
__u8 _pad8[48]; /* 0xcd0 */
struct edd_info eddbuf[EDDMAXNR]; /* 0xd00 */
__u8 _pad9[276]; /* 0xeec */

so we can use till 0x290.

and after those three dword, will still have 7 left.

>
>> diff --git a/arch/x86/boot/compressed/cmdline.c
>> b/arch/x86/boot/compressed/cmdline.c
>> index b4c913c..00678d3 100644
>> --- a/arch/x86/boot/compressed/cmdline.c
>> +++ b/arch/x86/boot/compressed/cmdline.c
>> @@ -17,6 +17,9 @@ static unsigned long get_cmd_line_ptr(void)
>> {
>> unsigned long cmd_line_ptr = real_mode->hdr.cmd_line_ptr;
>>
>> + if (real_mode->hdr.version >= 0x020c)
>> + cmd_line_ptr |= (u64)real_mode->hdr.ext_cmd_line_ptr <<
>> 32;
>> +
>> return cmd_line_ptr;
>> }
>
>
> No. hdr.version is information from the kernel to the bootloader; it is
> meaningless to look at it inside the kernel.
>
could remove them, but how about vmlinux elf.

when kexec vmlinux elf, it will fake one hdr, and fill version there.

> Same in a bunch of other places.
>

Thanks

Yinghai

\
 
 \ /
  Last update: 2012-11-21 20:41    [W:0.067 / U:0.552 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site