Re: [Minios-devel] [PATCH 03/40] arm64: add the boot code

[Huang Shijie <shijie.huang@xxxxxxx>]

On Tue, Nov 07, 2017 at 01:39:44PM +0000, Julien Grall wrote:
> Hi Shijie,
> 
> More question about the boot code...
> 
> On 03/11/17 03:11, Huang Shijie wrote:
> > +ENTRY(_start)
> > +    /* Save the FDT pointer */
> > +    mov     x20, x0
> > +
> > +    /* Calculate where we are */
> > +    bl      _calc_offset
> > +
> > +    PRINT("- Mini-OS booting -\n")
> > +
> > +    PRINT("- Setup CPU -\n")
> > +    /* Setup CPU for turning on the MMU. */
> > +    bl      _setup_cpu
> > +
> > +    PRINT("- Setup booting pagetable -\n")
> > +    /* Setup the initial page table. */
> > +    bl      _setup_initial_pgtable
> > +
> > +    /* Setup the identity mapping */
> > +    bl      _setup_idmap_pgtable
> > +
> > +    /* Load TTBRx */
> > +    msr     ttbr1_el1, x4
> > +    msr     ttbr0_el1, x5
> 
> First at all, this is not entirely obvious where x4 and x5 are been set.
> Proper documentation would be needed for that.
Okay, I will add more document for it.

> 
> Now, IIUC the code TTBR0_EL1 will contain the identity mappings. I was
> expecting to see it removed as soon as MMU is enabled. But this does not

Why should we remove it after the MMU is enabled?

Is there any problem if we keep it?

Thanks
Huang Shijie

_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/cgi-bin/mailman/listinfo/minios-devel