From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Mon, 20 Jan 2014 19:36:22 -0600
Message-ID: <CAGGHmKF+rZz-xWJnyJHPrv_D3QiNJS0hFKYL9CAXwYgd-aeMgQ@mail.gmail.com>
From: Steven Stallion <sstallion@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] about KTZERO mismatch in mkfile and mem.h
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On Mon, Jan 20, 2014 at 7:20 PM, Yoann Padioleau <pad@fb.com> wrote:
> Hi,
>
> in 9/pc/mem.h it says:
> /*
>  *  Address spaces
>  */
> #define KZERO           0xF0000000              /* base of kernel address space */
> #define KTZERO          (KZERO+0x100000)        /* first address in kernel text - 9load sits below */
>
>
> and in 9/pc/mkfile:
> # must match mem.h
> APBOOTSTRAP=0xF0003000
> KTZERO=0xF0100020
>
>
> so why the difference? what is this additional 20 for KTZERO?

pc kernels are a.out boot images. The extra 32 bytes are for the image
header. The difference varies by kernel - raw and uImage kernels don't
suffer from this; ELF as well depending on how smart the boot loader
is.

Steve