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From: WANG Cong <xiyou.wangcong@gmail.com>
To: kexec@lists.infradead.org
Subject: Re: Kexec & Memory Zones question
Date: Thu, 12 May 2011 10:03:03 +0000 (UTC)	[thread overview]
Message-ID: <iqgb8m$ruq$1@dough.gmane.org> (raw)
In-Reply-To: 20110511150908.GG31633@redhat.com

On Wed, 11 May 2011 11:09:08 -0400, Vivek Goyal wrote:

> We have discussed this in the past and due to various reasons the max
> amount of RAM you can boot your kernel from seems to be 896MB for x86_64
> and 512MB for 32bit. I shall have to open a previous thread with hpa to
> get exact numbers. So loading kernel even higher is not the solution.
> 

On the kexec-tools side, I think the limit is hard-coded,

./include/x86/x86-linux.h:250:#define DEFAULT_INITRD_ADDR_MAX 0x37FFFFFF

but we have,

        initrd_addr_max = DEFAULT_INITRD_ADDR_MAX;
        if (real_mode->protocol_version >= 0x0203) {
                initrd_addr_max = real_mode->initrd_addr_max;
                dbgprintf("initrd_addr_max is 0x%lx\n", initrd_addr_max);
        }


so, from the code, initrd_addr_max can be provided by the bootloader.

I remember on the kernel side there's also such a limit, but I can't
find where it is. I am wondering what prevents us from increasing this 
limit to 4G on i386 and even higher on x86_64.

Thanks.


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  reply	other threads:[~2011-05-12 10:03 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-04 18:35 Kexec & Memory Zones question Sujit V
2011-05-10  9:42 ` WANG Cong
2011-05-11 15:09 ` Vivek Goyal
2011-05-12 10:03   ` WANG Cong [this message]
2011-05-18  2:05     ` Sujit V
2011-05-18  2:40       ` WANG Cong

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