Re: [Xen-devel] [PATCH v10 06/13] efi: create new early memory allocator

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Dec 01, 2016 at 06:13:34AM -0700, Jan Beulich wrote:
> >>> On 30.11.16 at 14:04, <daniel.kiper@xxxxxxxxxx> wrote:
> > --- a/xen/common/efi/boot.c
> > +++ b/xen/common/efi/boot.c
> > @@ -98,6 +98,52 @@ static CHAR16 __initdata newline[] = L"\r\n";
> >  #define PrintStr(s) StdOut->OutputString(StdOut, s)
> >  #define PrintErr(s) StdErr->OutputString(StdErr, s)
> >
> > +#ifndef CONFIG_ARM
> > +
> > +/*
> > + * TODO: Enable EFI boot allocator on ARM.
> > + * This code can be common for x86 and ARM.
> > + * Things TODO on ARM before enabling ebmalloc:
> > + *   - estimate required EBMALLOC_SIZE value,
> > + *   - where (in which section) ebmalloc_mem[] should live; if in 
> > .bss.page_aligned
> > + *     then whole BSS zeroing have to be disabled in 
> > xen/arch/arm/arm64/head.S;
> > + *     though BSS should be initialized somehow before use of variables 
> > living there,
> > + *   - call free_ebmalloc_unused_mem() sowehere in init code.
> > + */
> > +
> > +#define EBMALLOC_SIZE      MB(1)
>
> The previous communication with Julien ended in it being acceptable
> to him for this to be zero for ARM for now, eliminating (or at least
> reducing) the #ifndef CONFIG_ARM guarded region(s).

That would be nice. Sadly it does not solve problem because ebmalloc()
and free_ebmalloc_unused_mem() are static and have to be #ifdef around
them too. Otherwise compiler complains because there are no callers for
both functions on ARM. So, I think that proposed solution is the simplest one.
I understand that you would like to reduce number of changes needed to
introduce EFI boot allocator on ARM. Though I am not sure how we can
simplify this step further.

Daniel

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