Re: [Minios-devel] [UNIKRAFT PATCHv4 18/43] plat/include: Define address offsets of boot stack and pagetable

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Julien,

> -----Original Message-----
> From: Julien Grall <julien.grall@xxxxxxx>
> Sent: 2018年7月9日 18:56
> To: Wei Chen <Wei.Chen@xxxxxxx>; minios-devel@xxxxxxxxxxxxxxxxxxxx;
> simon.kuenzer@xxxxxxxxx
> Cc: Kaly Xin <Kaly.Xin@xxxxxxx>; nd <nd@xxxxxxx>
> Subject: Re: [Minios-devel] [UNIKRAFT PATCHv4 18/43] plat/include: Define
> address offsets of boot stack and pagetable
> 
> On 09/07/18 11:10, Wei Chen wrote:
> > Hi Julien,
> 
> Hi Wei,
> 
> 
> >> -----Original Message-----
> >> From: Julien Grall <julien.grall@xxxxxxx>
> >> Sent: 2018年7月9日 4:19
> >> To: Wei Chen <Wei.Chen@xxxxxxx>; minios-devel@xxxxxxxxxxxxxxxxxxxx;
> >> simon.kuenzer@xxxxxxxxx
> >> Cc: Kaly Xin <Kaly.Xin@xxxxxxx>; nd <nd@xxxxxxx>
> >> Subject: Re: [Minios-devel] [UNIKRAFT PATCHv4 18/43] plat/include: Define
> >> address offsets of boot stack and pagetable
> >>
> >> Hi Wei,
> >>
> >> On 07/06/2018 10:03 AM, Wei Chen wrote:
> >>> If we place the boot stack and pagetable in BSS section. These
> >>> areas are not easy to be reused after changing to newstack. So
> >>
> >> s/newstack/a new stack/ or "the new stack".
> >>
> >
> >
> > Ok
> >
> >>> in Arm64, we want to place the pagetable and boot stack behind
> >>
> >> s/behind/after/
> >
> > Got it.
> >
> >>
> >>> the end of image.
> >>> In this case, once we change to newstack or we have new pagetable,
> >>> these two areas can be reclaimed very easy.
> >>
> >> I am wondering whether it would be worth to introduce an "init" section.
> >> This would make easier to reclaim the region and avoid hardcoded offset
> >> below.
> >
> > If we have a lot of such init functions or data, it would be good to have
> > a init section. If not, the freed small init section it's not easy managed.
> > Because VA and PA is 1:1 mapped.
> 
> I am not sure to understand how this would be difficult to manage? The
> region will be few tens KB. This is enough to allocate a lot of structure.
> 

If this region has tens of KB, I think it's valuable to do this.
But I think this feature is basic and common, and exceeds this
series scope. How do you think about it @Simon?

> Cheers,
> 
> --
> Julien Grall
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