Re: [Fwd: Overriding ACPI tables]

Re: [Fwd: Overriding ACPI tables]

[Eric Piel]

> Thomas Renninger wrote:
>> Peter: You wrote the syslinux stuff, right? What kind of luck is that :)
>> There currently is a discussion about being able to override ACPI tables
>> via initrd. The discussion is a bit stuck because the data is needed
>> earlier than initrd is unpacked and the hacks to make it work are not
>> accepted by Linus. I thought about adding another binary image to i386
>> boot protocol, similar to initrd= which contains data for very early
>> kernel boot initialization, but this would be a heavy hammer (but IMO
>> still better than only do it for kexec, another suggestion...) , I
>> better open a separate thread or pre-ask privately whether this makes
>> sense at all. It would be great if you could advise and possibly help to
>> convince so that we finally may find a solution accepted mainline.
> 
> We're putting in a mechanism for pushing larger tables already; we need 
> it for other things (in particular, the zones for E820 and EDD in the 
> boot_info_table are simply not big enough.)  That gives a generic 
> mechanism for sending arbitrary-sized binary images to the kernel.  That 
> would be the mechanism to use.
> 
> I believe it's in upstream as this merge window; it's definitely in 
> x86.git already.
Hi Peter,

Thank you for the pointer. You are talking about setup_data, right? I'll 
try to use it for reading the DSDT table. I have a couple of questions 
though:
* I can find reference of it only in setup_64.c, is it planned to add 
support also for 32bit? (That's a must for me)
* From inside the kernel, all I have to do is to add a hook inside 
parse_setup_data(), allocate memory and I'll be able to copy the data 
into this safe place, right?
* Is there any bootloader which already has support for this extension? 
  By chance, would you have a patch for grub?

See you,
Eric
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Re: [Fwd: Overriding ACPI tables]

[H. Peter Anvin]

Eric Piel wrote:
> Hi Peter,
> 
> Thank you for the pointer. You are talking about setup_data, right? I'll 
> try to use it for reading the DSDT table. I have a couple of questions 
> though:
> * I can find reference of it only in setup_64.c, is it planned to add 
> support also for 32bit? (That's a must for me)
> * From inside the kernel, all I have to do is to add a hook inside 
> parse_setup_data(), allocate memory and I'll be able to copy the data 
> into this safe place, right?
> * Is there any bootloader which already has support for this extension? 
>  By chance, would you have a patch for grub?
> 

It is planned, but not yet implemented, because the early reservations 
infrastructure hasn't been ported over to 32 bits yet.  The intent is to 
reserve this memory early and automatically.

So far this has only been used for large EFI SGI machines, so it's 
probably been implemented on ELILO only.  As far as Grub is concerned, I 
won't touch it with a ten-foot pole.

	-hpa