Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImageand ramdisk high

From: Yinghai Lu
Date: Sat Nov 24 2012 - 17:18:39 EST


On Sat, Nov 24, 2012 at 1:38 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 11/24/2012 01:30 PM, Yinghai Lu wrote:
>>>
>>>
>>> So, given the mess we now have on our hands... any suggestions how to
>>> best
>>> solve it? There is the option of simply declaring old kexec binaries
>>> broken; they will then not work reliably with newer kernels, if they even
>>> work reliably now -- it is hard to know for certain.
>>
>>
>> yes, if the user updates kernel to be kexeced, then would be
>> reasonable to ask them to
>> update kexec-tools.
>>
>
> Careful... consider the people who use a kexec-based solution as
> bootloaders.

yes, those may not update kexec in the flash...

then, may need to use another bit in xloadflags to tell new kernel if
need to check ext_...

Field name: xloadflags
Type: modify (obligatory)
Offset/size: 0x236/2
Protocol: 2.12+

This field is a bitmask.

Bit 0 (read): CAN_BE_LOADED_ABOVE_4G
- If 1, kernel/boot_params/cmdline/ramdisk can be above 4g,
set by kernel.

Bit 1 (write): LOADED_ABOVE_4G
- If 1, kernel/boot_params/cmdline/ramdisk is loaded above 4g,
set by bootloader, and kernel will check ext_ramdisk_image,
ext_ramdisk_size and ext_cmd_line_ptr.
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