Re: [ECOS] Redboot (i386pc with IDE Flash)

[David Brennan <david at brennanhome dot com>]

Ram size would not be a typical concern in a PC target (I think). We are 
running with 256M of RAM, and probably using less that 64M of that. So 
I'd be willing to try and juggle the memory, if you could point me in 
the correct direction.
Yes, I can load an application with GRUB off the network, but it is not 
as convenient as with GDB. (Need to set up TFTP/FTP server? GRUB 
documentation was not clear on what (ND) was supported when I scanned 
it). But debugging serial would be a real pain. (And one of our apps 
will be using both available serial ports on the board for IO, so in 
that case it will not be feasible.)

Thanks
David Brennan

Nick Garnett wrote:

> David Brennan <eCos@brennanhome.com> writes:
>
>  
>
> > Nick,
> > Can you easily summarize why redboot does not work with GRUB? This is
> > a feature that I am going to be looking for in the near future. Is it
> > just something that no one has tackled? Or is it impossible for some
> > reason? I am working on a VME based PC and have several available
> > target machines, but only one floppy. So I want to be able to boot off
> > of CF and still load/debug using Ethernet. If this is possible but
> > just needs work, can you give me some pointers as to what needs to be
> > done?
> >
> >    
>
> RAM applications load at the 1MB boundary, so RedBoot needs to live in
> the bottom 640k. However, GRUB also uses the bottom 640k, so we would
> need to load a GRUB RedBoot above the 1MB boundary. This means that we
> would then have to shuffle RAM applications up, probably to 2MB. This
> causes an incompatibility, and also means that when not using a GRUB
> RedBoot, we waste a megabyte of memory.
>
> We also end up with the silly situation of using a bootloader to load
> a bootloader to load the application. It was thought much better to go
> straight to the application from GRUB. RedBoot on the PC has much less
> functionality than elsewhere since there is no flash. All it can
> provide is loading an application from the network, and GDB
> support. GRUB can load from the network, and by building the stubs
> into the application we get GDB support. So RedBoot is largely
> redundant, and no effort has been put into making it work.
>
>
>  

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