Re: [Xen-devel] [PATCH v3 1/2] efi: remove old SetVirtualAddressMap() arrangement

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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On Wed, Oct 23, 2019 at 05:15:42PM +0200, Jan Beulich wrote:
> On 13.10.2019 00:11, Marek Marczykowski-Górecki  wrote:
> > @@ -1099,9 +1096,6 @@ static void __init efi_exit_boot(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *Syste
> >  
> >      /* Adjust pointers into EFI. */
> >      efi_ct = (void *)efi_ct + DIRECTMAP_VIRT_START;
> > -#ifdef USE_SET_VIRTUAL_ADDRESS_MAP
> > -    efi_rs = (void *)efi_rs + DIRECTMAP_VIRT_START;
> > -#endif
> 
> This doesn't get re-instated in any way by patch 2. 

This commit remove dead code.

> How come you
> get away without? 

The second patch doesn't just fix what was under #ifdef
USE_SET_VIRTUAL_ADDRESS_MAP. It does a completely different approach to
using SetVirtualAddressMap. See below.

On Wed, Oct 23, 2019 at 05:26:48PM +0200, Jan Beulich wrote:
> On 13.10.2019 00:11, Marek Marczykowski-Górecki  wrote:
> > @@ -1591,10 +1576,6 @@ void __init efi_init_memory(void)
> >          return;
> >      }
> >  
> > -#ifdef USE_SET_VIRTUAL_ADDRESS_MAP
> > -    efi_rs->SetVirtualAddressMap(efi_memmap_size, efi_mdesc_size,
> > -                                 mdesc_ver, efi_memmap);
> > -#else
> >      /* Set up 1:1 page tables to do runtime calls in "physical" mode. */
> 
> This comment, btw, also wants either adjusting or removing.

No, it still setup 1:1 page tables for the runtime calls, exactly as it
was before. This is also why I don't need to adjust efi_rs. The only
difference is now (with patch 2) we tell UEFI about it. But the actual
address space layout for the runtime calls is exactly as it was before.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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