On 29/06/07 20:56 +0200, Stefan Reinauer wrote:
Jordan's talk here at the OLS described how LinuxBIOS relocates itself from the very low space to TOM during the boot process. I think we should think carefully about this stuff. Will any OS ever claim to be copied into the low 1M?
Eric can correct me, but from what I can tell, the intent of the extra copy is to allow any arbitrary application to run - even those that are less then responsible about where they go in memory. We generalized a little bit in our talk - what happens in reality in the elf loader is that parts of the payload that would interfere with the loader are copied into a temporary buffer, and later, LB copies itself out of the way, and replaces the missing chunks back into their rightful place. I don't believe this code runs all the time - just in those situations where LB code is at danger.
Its a little hackish, but I would prefer to have that rather then put restrictions on the payload - we can hope that most payloads are friendly, but we shouldn't restrict the ones that aren't.
--- Jordan Crouse Senior Linux Engineer Advanced Micro Devices, Inc. <www.amd.com/embeddedprocessors>