[RFC PATCH] arm64/efi: remove /chosen/linux,uefi-stub-kern-ver DT property

[RFC PATCH] arm64/efi: remove /chosen/linux,uefi-stub-kern-ver DT property

[Ard Biesheuvel]

With the stub to kernel interface being promoted to a proper interface
so that other agents than the stub can boot the kernel proper in EFI
mode, we can remove the linux,uefi-stub-kern-ver field, considering
that its original purpose was to prevent this from happening in the
first place.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 Documentation/arm/uefi.txt         | 2 --
 drivers/firmware/efi/libstub/fdt.c | 9 ---------
 2 files changed, 11 deletions(-)

diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt
index 7b3fdfe0f7ba..6543a0adea8a 100644
--- a/Documentation/arm/uefi.txt
+++ b/Documentation/arm/uefi.txt
@@ -58,5 +58,3 @@ linux,uefi-mmap-desc-size | 32-bit | Size in bytes of each entry in the UEFI
 --------------------------------------------------------------------------------
 linux,uefi-mmap-desc-ver  | 32-bit | Version of the mmap descriptor format.
 --------------------------------------------------------------------------------
-linux,uefi-stub-kern-ver  | string | Copy of linux_banner from build.
---------------------------------------------------------------------------------
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index a7e87cd582f2..60a11551fc15 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -116,15 +116,6 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 	if (status)
 		goto fdt_set_fail;
 
-	/*
-	 * Add kernel version banner so stub/kernel match can be
-	 * verified.
-	 */
-	status = fdt_setprop_string(fdt, node, "linux,uefi-stub-kern-ver",
-			     linux_banner);
-	if (status)
-		goto fdt_set_fail;
-
 	return EFI_SUCCESS;
 
 fdt_set_fail:
-- 
1.9.1

Re: [RFC PATCH] arm64/efi: remove /chosen/linux,uefi-stub-kern-ver DT property

[Mark Rutland]

Hi Ard,

On Thu, Sep 24, 2015 at 10:46:30PM +0100, Ard Biesheuvel wrote:
> With the stub to kernel interface being promoted to a proper interface
> so that other agents than the stub can boot the kernel proper in EFI
> mode, we can remove the linux,uefi-stub-kern-ver field, considering
> that its original purpose was to prevent this from happening in the
> first place.

I'm not oppposed to this, but this change needs to be folded together with the
other documentation updates necessary for this to become a stable ABI, as
discussed in the other thread [1].

Thanks,
Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-September/369001.html

> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  Documentation/arm/uefi.txt         | 2 --
>  drivers/firmware/efi/libstub/fdt.c | 9 ---------
>  2 files changed, 11 deletions(-)
> 
> diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt
> index 7b3fdfe0f7ba..6543a0adea8a 100644
> --- a/Documentation/arm/uefi.txt
> +++ b/Documentation/arm/uefi.txt
> @@ -58,5 +58,3 @@ linux,uefi-mmap-desc-size | 32-bit | Size in bytes of each entry in the UEFI
>  --------------------------------------------------------------------------------
>  linux,uefi-mmap-desc-ver  | 32-bit | Version of the mmap descriptor format.
>  --------------------------------------------------------------------------------
> -linux,uefi-stub-kern-ver  | string | Copy of linux_banner from build.
> ---------------------------------------------------------------------------------
> diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
> index a7e87cd582f2..60a11551fc15 100644
> --- a/drivers/firmware/efi/libstub/fdt.c
> +++ b/drivers/firmware/efi/libstub/fdt.c
> @@ -116,15 +116,6 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
>  	if (status)
>  		goto fdt_set_fail;
>  
> -	/*
> -	 * Add kernel version banner so stub/kernel match can be
> -	 * verified.
> -	 */
> -	status = fdt_setprop_string(fdt, node, "linux,uefi-stub-kern-ver",
> -			     linux_banner);
> -	if (status)
> -		goto fdt_set_fail;
> -
>  	return EFI_SUCCESS;
>  
>  fdt_set_fail:
> -- 
> 1.9.1
> 

Re: [RFC PATCH] arm64/efi: remove /chosen/linux,uefi-stub-kern-ver DT property

[Ard Biesheuvel]

On 24 September 2015 at 16:13, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> wrote:
> Hi Ard,
>
> On Thu, Sep 24, 2015 at 10:46:30PM +0100, Ard Biesheuvel wrote:
>> With the stub to kernel interface being promoted to a proper interface
>> so that other agents than the stub can boot the kernel proper in EFI
>> mode, we can remove the linux,uefi-stub-kern-ver field, considering
>> that its original purpose was to prevent this from happening in the
>> first place.
>
> I'm not oppposed to this, but this change needs to be folded together with the
> other documentation updates necessary for this to become a stable ABI, as
> discussed in the other thread [1].
>

Yes, you are quite right (and apologies to Stefano and Shannon for not
cc'ing them on this patch)

It would be good to remove this /before/ promoting any of this to stable ABI.

-- 
Ard.



> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-September/369001.html
>
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> ---
>>  Documentation/arm/uefi.txt         | 2 --
>>  drivers/firmware/efi/libstub/fdt.c | 9 ---------
>>  2 files changed, 11 deletions(-)
>>
>> diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt
>> index 7b3fdfe0f7ba..6543a0adea8a 100644
>> --- a/Documentation/arm/uefi.txt
>> +++ b/Documentation/arm/uefi.txt
>> @@ -58,5 +58,3 @@ linux,uefi-mmap-desc-size | 32-bit | Size in bytes of each entry in the UEFI
>>  --------------------------------------------------------------------------------
>>  linux,uefi-mmap-desc-ver  | 32-bit | Version of the mmap descriptor format.
>>  --------------------------------------------------------------------------------
>> -linux,uefi-stub-kern-ver  | string | Copy of linux_banner from build.
>> ---------------------------------------------------------------------------------
>> diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
>> index a7e87cd582f2..60a11551fc15 100644
>> --- a/drivers/firmware/efi/libstub/fdt.c
>> +++ b/drivers/firmware/efi/libstub/fdt.c
>> @@ -116,15 +116,6 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
>>       if (status)
>>               goto fdt_set_fail;
>>
>> -     /*
>> -      * Add kernel version banner so stub/kernel match can be
>> -      * verified.
>> -      */
>> -     status = fdt_setprop_string(fdt, node, "linux,uefi-stub-kern-ver",
>> -                          linux_banner);
>> -     if (status)
>> -             goto fdt_set_fail;
>> -
>>       return EFI_SUCCESS;
>>
>>  fdt_set_fail:
>> --
>> 1.9.1
>>