Re: error: core image is too big (0xXXXXXX > 0x78000)

[Andrey Borzenkov]

В Thu, 7 Nov 2013 20:37:53 -0600
Glenn Washburn <address@hidden> пишет:

> This only happens on i386-pc and i386 pxe.
> 
> Can anyone explain or point to documentation as to why the core image
> can't be larger than 0x78000 for i386?
> 
> It appears that this check is to prevent grub from occupying some of
> the upper memory area.  Why can't grub use the upper memory?  Why
> doesn't grub use unreal mode to access the extended memory?  If it does
> use these memory regions, why is there this limit?
> 

grub does use protected mode, but core.img is loaded very early in real
mode, where available memory is quite limited. For this reason core.img
should be as small as possible and contain just enough to access the
rest of grub modules which can be loaded later after switch to
protected mode.

I do not know where exact number comes from; but absolute limit is 640k
anyway and part of it is already taken.

> Any insight is appreciated,
> Glenn
> 
> 
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