linux-kernel - Re: [Fastboot] [CFT] ELF Relocatable x86 and x86

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Date:	Mon, 31 Jul 2006 19:34:57 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [Fastboot] [CFT] ELF Relocatable x86 and x86_64 bzImages

Eric W. Biederman wrote:
> 
>> Ok. I am decompressing the kernel to 16MB and after reducing 1MB of
>> CONFIG_PHYSICAL_START I am left with 15MB which is not 4M aligned
>> hence I seems to be running into it.
>>
>> I changed it to
>>
>> if ((u32)output) & 0x3fffff)
>>
>> and kdump kernel booted fine. But this will run into issues if I load
>> kernel at 1MB.
>>
>> I got a dump question. Why do I have to load the kernel at 4MB alignment?
>> Existing kernel boots loads at 1MB, which is non 4MB aligned and it works
>> fine?
> 
> 4MB is a little harsh, but I haven't worked through what the exact rules
> are, I know 4MB is the worst case alignment for arch/i386.
> 

4 MB would be worst case for i386; 2 MB for x86-64.  Actually the x86-64 
worst case would be gigabyte, but that's more than a little bit extreme.

	-hpa
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