linux-kernel - Re: [PATCH] x86: make sure wakeup code is below 1M -v2

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Message-Id: <1258010067.3802.11.camel@localhost.localdomain>
Date:	Thu, 12 Nov 2009 15:14:27 +0800
From:	ykzhao <yakui.zhao@...el.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH] x86: make sure wakeup code is below 1M -v2

On Thu, 2009-11-12 at 13:21 +0800, Yinghai Lu wrote:
> ykzhao wrote:
> > On Thu, 2009-11-12 at 11:12 +0800, Yinghai Lu wrote:
> >> ykzhao wrote:
> >>> On Thu, 2009-11-12 at 03:05 +0800, Yinghai Lu wrote:
> >>>> ykzhao wrote:
> >>>>> On Wed, 2009-11-11 at 10:27 +0800, Yinghai Lu wrote:
> >>>>>> try to find_e820_area/reserve_early, and call acpi_reserve_memory early
> >>>>>>
> >>>>>> to get area is below 1M
> >>>>>>
> >>>>>> -v2: change function name to acpi_reserve_wakeup_memory according to Rafael
> >>>>> It seems that the function of find_e820_area is called in several
> >>>>> places.
> >>>>>    >Initmem_init: bootmap = find_e820_area(0, end_pfn<<PAGE_SHIFT,
> >>>>> bootmap_size, PAGE_SIZE);
> >>>>>    
> >>>>> If we also call it in the acpi_reserve_wakeup_memory, do we get the same
> >>>>> base address as that obtained in initmem_init?
> >>>> no. find_e820_area will check the reserve res array that could be updated by reserve_early.
> >>> It will check the reserved region array when calling the function of
> >>> find_e820_area. 
> >>> But it seems that the array is not updated when the find_e820_area is
> >>> called in the function of initmem_init.
> >> right after that will use reserve_bootmem for those range in initmem_init.
> > Yes. The reserve_bootmem is called for the range in initmem_init.
> > But the reserved_early array is not updated.
> 
> it is not needed anymore because bootmem for that node is ready at that point, could use 
> reserve_bootmem_node directly. and before that early_res_to_bootmem will convert that early resource that 
> fall into that node range to bootmem reserved too.
After the bootmem allocator is initialized, the early_res_to_bootmem
will convert the resource in reserved_early array and reserve them in
the bootmem. 

In this patch the find_e820_area is used in the
acpi_reserve_wakeup_memory, which is called after initializing the
bootmem allocator.
Can we still use the find_e820_area after the bootmem allocator is
initialized? 
It seems that the bootmem bitmap is also found by using the
find_e820_area. But we don't update the reserved_early array any more.
Maybe we will get the overlap address with the bootmem bitmap for the
wakeup code.

thanks.
> 
> please check code setup_node_bootmem/early_node_mem/early_res_to_bootmem ...and reserve_bootmem_node...

> 
> YH

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