From: Yinghai Lu <yinghai@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"Eric W. Biederman" <ebiederm@xmission.com>,
linux-kernel@vger.kernel.org, Rob Landley <rob@landley.net>,
Matt Fleming <matt.fleming@intel.com>
Subject: Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high
Date: Wed, 21 Nov 2012 10:59:46 -0800 [thread overview]
Message-ID: <CAE9FiQUSjRT-r5ZE3WHVaKkUOhwFWkm9CTCv1Aa63DOsfMQMiQ@mail.gmail.com> (raw)
In-Reply-To: <50AD0CA1.8000904@zytor.com>
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
next prev parent reply other threads:[~2012-11-21 18:59 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-21 7:15 [PATCH v3 00/12] x86, boot, 64bit: Add support for loading ramdisk and bzImage high Yinghai Lu
2012-11-21 7:15 ` [PATCH v3 01/12] x86, boot: move verify_cpu.S after 0x200 Yinghai Lu
2012-11-21 17:23 ` H. Peter Anvin
2012-11-21 19:45 ` Yinghai Lu
2012-11-21 19:50 ` H. Peter Anvin
2012-11-21 20:15 ` Yinghai Lu
2012-11-22 5:48 ` Eric W. Biederman
[not found] ` <3178cb29-0e9e-44d2-b21f-45c53f38980a@email.android.com>
2012-11-22 11:27 ` Eric W. Biederman
2012-11-24 7:00 ` Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 02/12] x86, boot: Move lldt/ltr out of 64bit code section Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 03/12] x86, 64bit: set extra ident page table for whole kernel range Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 04/12] x86, 64bit: add support for loading kernel above 512G Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 05/12] x86: Merge early_reserve_initrd for 32bit and 64bit Yinghai Lu
2012-11-21 7:40 ` Pekka Enberg
2012-11-21 7:16 ` [PATCH v3 06/12] x86: add get_ramdisk_image/size Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 07/12] x86, boot: add get_cmd_line_ptr() Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 08/12] x86, boot: Don't check if cmd_line_ptr is accessible in misc/decompressor() Yinghai Lu
2012-11-21 17:21 ` H. Peter Anvin
2012-11-21 19:18 ` Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 09/12] x86, boot: update cmd_line_ptr to unsigned long Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 10/12] x86: use io_remap to access real_mode_data Yinghai Lu
2012-11-21 7:16 ` [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high Yinghai Lu
2012-11-21 17:17 ` H. Peter Anvin
2012-11-21 18:59 ` Yinghai Lu [this message]
2012-11-21 19:18 ` H. Peter Anvin
2012-11-22 5:56 ` Yinghai Lu
[not found] ` <a1ca794a-09d4-4d36-8c8c-67100cb3696e@email.android.com>
2012-11-22 6:47 ` Yinghai Lu
2012-11-22 6:58 ` Yinghai Lu
2012-11-22 15:59 ` H. Peter Anvin
2012-11-22 18:28 ` Yinghai Lu
2012-11-22 18:37 ` H. Peter Anvin
2012-11-22 18:50 ` Yinghai Lu
2012-11-22 18:51 ` H. Peter Anvin
2012-11-22 20:18 ` Yinghai Lu
2012-11-22 20:20 ` H. Peter Anvin
2012-11-22 20:29 ` Yinghai Lu
2012-11-22 20:50 ` H. Peter Anvin
2012-11-22 21:02 ` H. Peter Anvin
2012-11-22 22:13 ` Yinghai Lu
2012-11-24 12:37 ` Eric W. Biederman
2012-11-24 17:32 ` H. Peter Anvin
[not found] ` <CAE9FiQV0Q0fi7TrNjihdsUt0ueT4LLON4o+JEmX6ry9S6AU-ug@mail.gmail.com>
2012-11-24 18:24 ` H. Peter Anvin
2012-11-24 19:50 ` H. Peter Anvin
2012-11-24 21:30 ` Yinghai Lu
2012-11-24 21:38 ` H. Peter Anvin
2012-11-24 22:18 ` Yinghai Lu
2012-11-24 22:32 ` H. Peter Anvin
2012-11-24 23:24 ` Yinghai Lu
2012-11-24 23:50 ` Eric W. Biederman
2012-11-25 0:04 ` H. Peter Anvin
2012-11-25 0:11 ` Yinghai Lu
2012-11-25 5:50 ` Yinghai Lu
2012-11-25 5:52 ` H. Peter Anvin
2012-11-25 6:09 ` Yinghai Lu
2012-11-25 0:04 ` Yinghai Lu
2012-11-25 0:06 ` H. Peter Anvin
2012-11-21 7:16 ` [PATCH v3 12/12] x86: remove 1024g limitation for kexec buffer on 64bit Yinghai Lu
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