Lars Kellogg-Stedman wrote:
>
> For instance, it would be nice if the last action when rebooting a linux
> system were (optionally) to load and execute a new kernel image, rather
> than reset the system.
I do this quite frequently on embedded systems. Rather than try to
write boot roms with network protocols, I just put a Linux kernel
in the flash rom. They can boot up using diskless NFS (or whatever
you want), and are hacked to reserve a chunk of contiguous physical
memory for loading the new kernel. I have a rather trivial program
that will mmap() the memory and copy a kernel file there. Then I
modified the machine_restart() to take a reboot command with a
starting address. The "gorom" function then disables interrupts,
mmu, cache, and jumps to the starting address of the new code.
The kernels I boot are all Linux/PPC compressed zImage. Since
they relocate themselves and uncompress the kernel to the proper
memory location, it doesn't matter where they are initially loaded
in physical memory. Works very well.
I chose to reserved a big piece of physical memory because it was
easy to do. There are several variations on allocating memory for
the new kernel, with associated modifications to boot loader wrappers.
I am sure you could write a driver that would coalesce memory for the
new image that would work with any kernel, so from one kernel you
could just boot another.
-- Dan
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This archive was generated by hypermail 2b29 : Tue Feb 29 2000 - 21:00:18 EST