[ros-dev] multiboot.S patch in need of review, please
ionucu at videotron.ca
Wed Jan 26 20:27:33 CET 2005
Hartmut Birr wrote:
> Royce Mitchell III schrieb:
>> I was in a strange mood and decided to try to implement something
>> Alex wanted.
>> I've done the leg-work on this, but need someone familiar with
>> boot-up and particularly smp to review this patch. I do not have
>> access to smp, and do not wish to break it.
>> This patch implements the /3G switch from within multiboot.S, which
>> is necessary in order to configure the page tables correctly.
>> I noticed some code in _main() that was processing a 3G switch on the
>> command-line, and I can't understand how it could possibly work
>> because it's not readjusting the page tables, nor does it transition
>> to the 0xC0000000 address space that I can see, so I don't think that
>> code actually works. If it does, I'm glad to be proved wrong.
>> The patch I've written makes an assumption that lowmem is available
>> when application processors execute the code. I can't seem to figure
>> out how or where the application processor(s) actually get told to
>> start executing, so I don't know if this assumption is true. However,
>> if it's not true, if someone could point me to the code that inits
>> the application processors, I can configure them to pass the needed
>> info via %ebp or something.
>> Finally, I haven't actually tried booting this code. I wanted someone
>> to review it first for obvious blunders, or to tell me, if necessary,
>> that I've wasted my time ;) If I'm on the right track then, when
>> I'm feeling motivated enough again, I will actually try booting it.
>> Ros-dev mailing list
>> Ros-dev at reactos.com
> I think your patch will never work. There are used some offsets which
> based on the '/3GB' switch and other ones are hard coded by
> KERNEL_BASE. IMHO, the boot code should not search for the '/3GB'
> option. The kernel base address must be send by freeldr.
> The boot code must not contain any KERNEL_BASE value. I've add your
> patch to my source tree. On the smp machine, ros reboots in the very
> early boot phase. It is before the call to _main.
> - Hartmut
I think freeldr shoudl be modified to PE load the boot drivers and
ntoskrnl, instead of just memory dumping. This should remove most of the
bss hacks which use kernel_base, and the rest should use whatever
freeldr pushes on the loader_block. For now, we were simply testing some
things, and Royce's patch still helps a lot.
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