Re: [RFC] general-usage real-mode loader

[phcoder <phcoder@gmail.com>]

I checked the archive found the thread "Idea: Move kernel to upper
memory". But what is discussed there is much more general about general
memory layout. Here I wanted to speak about just one function.
Vladimir 'phcoder' Serbinenko
Robert Millan wrote:
> On Fri, Sep 05, 2008 at 07:27:51PM +0200, phcoder wrote:
>> Hello. A long time ago I written a C+asm code which loads any given code
>> at any real-mode location, then puts machine in correct state and then
>> launches the kernel. I can modify this code to suit GRUB2. Then loading
>> realmode kernel would work like this:
>> 1) copy helper asm to last kb of lower memory
>> 2) jump to the helper
>> 3) helper copies from upper memory the kernel
>> 4) turn A10 bug back on if necessary
>> 5) go to RM
>> 6) prepare registers
>> 7) jump to the kernel
>>
>> This protocol is very flexible and as such could be used by all loaders
>> which load kernel in realmode or even in PM (skip step 5, do steps 6-7
>> in 32-bit mode) except for changing page tables. Such a helper can be
>> easily implemented as module and so help us removing asm-parts of
>> loaders from the kernel. If I recieve greenlight for it, I implement it.
> 
> Maybe I'm confusing this with something else, but isn't this what both Bean
> and Vesa implemented separately, and are currently discussing in another
> thread?
> 
> (the goal there was to move BIOS wrappers out of kern/i386/pc/startup.S)
>