* [RFC PATCH] arm64: Image: Allow the appending of a device tree binary
@ 2015-06-04 9:35 Yang Yingliang
2015-06-04 10:04 ` Mark Rutland
2015-06-04 10:07 ` Dave Martin
0 siblings, 2 replies; 3+ messages in thread
From: Yang Yingliang @ 2015-06-04 9:35 UTC (permalink / raw)
To: catalin.marinas, will.deacon; +Cc: linux-arm-kernel, linux-kernel, bones
This patch provides the ability to boot using a device tree that is appended
to the raw binary Image (e.g. cat Image <filename>.dtb > Image_w_dtb).
Both BE and LE conditions are tested.
Got references from e2a6a3aa ("ARM: zImage: Allow the appending of a device tree binary").
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
arch/arm64/Kconfig | 11 +++++++++++
arch/arm64/kernel/head.S | 12 ++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 17 +++++++++++++++++
3 files changed, 40 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7796af4..d402448 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -660,6 +660,17 @@ endmenu
menu "Boot options"
+config ARM64_APPENDED_DTB
+ bool "Use appended device tree blob to Image"
+ depends on OF
+ help
+ With this option, the boot code will look for a device tree binary
+ (DTB) appended to Image
+ (e.g. cat Image <filename>.dtb > Image_w_dtb).
+
+ With this option, the size of Image will be extended to be 2MB aligned.
+ The 2MB memory followed by Image is used for FDT blob.
+
config CMDLINE
string "Default kernel command string"
default ""
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 19f915e..ac00c8a 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -274,6 +274,18 @@ ENDPROC(preserve_boot_args)
* The dtb must be 8-byte aligned and live in the first 512M of memory.
*/
__vet_fdt:
+#ifdef CONFIG_ARM64_APPENDED_DTB
+ ldr x21, =_edata
+ add x21, x21, x28
+ ldr w0, [x21]
+#ifndef __AARCH64EB__
+ ldr w1, =0xedfe0dd0 // FDT magic word
+#else
+ ldr w1, =0xd00dfeed
+#endif
+ cmp w0, w1
+ b.ne 1f // no FDT found
+#endif
tst x21, #0x7
b.ne 1f
cmp x21, x24
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index a2c2986..c71bac3 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -54,6 +54,18 @@ PECOFF_FILE_ALIGNMENT = 0x200;
#define PECOFF_EDATA_PADDING
#endif
+/*
+ * Set FDT pointer 2MB aligned to ensure
+ * it don't cross a 2-megabyte boundary.
+ */
+FDT_FILE_ALIGNMENT = (1 << 21);
+#ifdef CONFIG_ARM64_APPENDED_DTB
+#define FDT_EDATA_PADDING \
+ .fdt_edata_padding : { BYTE(0); . = ALIGN(FDT_FILE_ALIGNMENT); }
+#else
+#define FDT_EDATA_PADDING
+#endif
+
#ifdef CONFIG_DEBUG_ALIGN_RODATA
#define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
@@ -149,8 +161,13 @@ SECTIONS
_sdata = .;
RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
PECOFF_EDATA_PADDING
+ FDT_EDATA_PADDING /* 2MB aligned */
_edata = .;
+#ifdef CONFIG_ARM64_APPENDED_DTB
+ . += (1 << 21); /* maximum 2MB for FDT blob */
+#endif
+
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
--
1.8.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] arm64: Image: Allow the appending of a device tree binary
2015-06-04 9:35 [RFC PATCH] arm64: Image: Allow the appending of a device tree binary Yang Yingliang
@ 2015-06-04 10:04 ` Mark Rutland
2015-06-04 10:07 ` Dave Martin
1 sibling, 0 replies; 3+ messages in thread
From: Mark Rutland @ 2015-06-04 10:04 UTC (permalink / raw)
To: Yang Yingliang
Cc: Catalin Marinas, Will Deacon, bones, linux-kernel, linux-arm-kernel
Hi,
On Thu, Jun 04, 2015 at 10:35:04AM +0100, Yang Yingliang wrote:
> This patch provides the ability to boot using a device tree that is appended
> to the raw binary Image (e.g. cat Image <filename>.dtb > Image_w_dtb).
>
> Both BE and LE conditions are tested.
>
> Got references from e2a6a3aa ("ARM: zImage: Allow the appending of a device tree binary").
NAK for this as it stands. I really don't want to see appended DTB for
arm64.
We needed it for arm because old bootloaders didn't know how to pass a
DTB to the kernel. For arm64 DTB has always been a requirement, so
there's no legacy bootloader to support, and the rationale from arm does
not apply.
Adding appended DTB to arm64 encourages the broken assumption that
kernel and DTB are intimately coupled. It relies on arbitrary
limitations that are difficult and/or impossible to change in future in
a compatible fashion (e.g. the 2M carveout you make for the DT to live
in), and also makes it hard to replace either the kernel or DTB becuase
in the resulting Image there's no clear distinction between the two.
It's simply far too fragile.
Thanks,
Mark.
>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> arch/arm64/Kconfig | 11 +++++++++++
> arch/arm64/kernel/head.S | 12 ++++++++++++
> arch/arm64/kernel/vmlinux.lds.S | 17 +++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7796af4..d402448 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -660,6 +660,17 @@ endmenu
>
> menu "Boot options"
>
> +config ARM64_APPENDED_DTB
> + bool "Use appended device tree blob to Image"
> + depends on OF
> + help
> + With this option, the boot code will look for a device tree binary
> + (DTB) appended to Image
> + (e.g. cat Image <filename>.dtb > Image_w_dtb).
> +
> + With this option, the size of Image will be extended to be 2MB aligned.
> + The 2MB memory followed by Image is used for FDT blob.
> +
> config CMDLINE
> string "Default kernel command string"
> default ""
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 19f915e..ac00c8a 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -274,6 +274,18 @@ ENDPROC(preserve_boot_args)
> * The dtb must be 8-byte aligned and live in the first 512M of memory.
> */
> __vet_fdt:
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + ldr x21, =_edata
> + add x21, x21, x28
> + ldr w0, [x21]
> +#ifndef __AARCH64EB__
> + ldr w1, =0xedfe0dd0 // FDT magic word
> +#else
> + ldr w1, =0xd00dfeed
> +#endif
> + cmp w0, w1
> + b.ne 1f // no FDT found
> +#endif
> tst x21, #0x7
> b.ne 1f
> cmp x21, x24
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index a2c2986..c71bac3 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -54,6 +54,18 @@ PECOFF_FILE_ALIGNMENT = 0x200;
> #define PECOFF_EDATA_PADDING
> #endif
>
> +/*
> + * Set FDT pointer 2MB aligned to ensure
> + * it don't cross a 2-megabyte boundary.
> + */
> +FDT_FILE_ALIGNMENT = (1 << 21);
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> +#define FDT_EDATA_PADDING \
> + .fdt_edata_padding : { BYTE(0); . = ALIGN(FDT_FILE_ALIGNMENT); }
> +#else
> +#define FDT_EDATA_PADDING
> +#endif
> +
> #ifdef CONFIG_DEBUG_ALIGN_RODATA
> #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
> #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
> @@ -149,8 +161,13 @@ SECTIONS
> _sdata = .;
> RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
> PECOFF_EDATA_PADDING
> + FDT_EDATA_PADDING /* 2MB aligned */
> _edata = .;
>
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + . += (1 << 21); /* maximum 2MB for FDT blob */
> +#endif
> +
> BSS_SECTION(0, 0, 0)
>
> . = ALIGN(PAGE_SIZE);
> --
> 1.8.0
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] arm64: Image: Allow the appending of a device tree binary
2015-06-04 9:35 [RFC PATCH] arm64: Image: Allow the appending of a device tree binary Yang Yingliang
2015-06-04 10:04 ` Mark Rutland
@ 2015-06-04 10:07 ` Dave Martin
1 sibling, 0 replies; 3+ messages in thread
From: Dave Martin @ 2015-06-04 10:07 UTC (permalink / raw)
To: Yang Yingliang
Cc: catalin.marinas, will.deacon, bones, linux-kernel, linux-arm-kernel
Hi,
On Thu, Jun 04, 2015 at 05:35:04PM +0800, Yang Yingliang wrote:
> This patch provides the ability to boot using a device tree that is appended
> to the raw binary Image (e.g. cat Image <filename>.dtb > Image_w_dtb).
>
> Both BE and LE conditions are tested.
>
> Got references from e2a6a3aa ("ARM: zImage: Allow the appending of a device tree binary").
Passing the DTB is really the responsibility of the bootloader.
ARM_APPENDED_DTB was a transitional hack to allow non-DT-aware
bootloaders to boot new kernels that require a DT for arch/arm.
For arm64 DT has been required from the start, as mandated in
Documentation/arm64/booting.txt -- there are no "legacy" bootloaders to
support.
Can you explain your rationale for this change?
Cheers
---Dave
>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> arch/arm64/Kconfig | 11 +++++++++++
> arch/arm64/kernel/head.S | 12 ++++++++++++
> arch/arm64/kernel/vmlinux.lds.S | 17 +++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7796af4..d402448 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -660,6 +660,17 @@ endmenu
>
> menu "Boot options"
>
> +config ARM64_APPENDED_DTB
> + bool "Use appended device tree blob to Image"
> + depends on OF
> + help
> + With this option, the boot code will look for a device tree binary
> + (DTB) appended to Image
> + (e.g. cat Image <filename>.dtb > Image_w_dtb).
> +
> + With this option, the size of Image will be extended to be 2MB aligned.
> + The 2MB memory followed by Image is used for FDT blob.
> +
> config CMDLINE
> string "Default kernel command string"
> default ""
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 19f915e..ac00c8a 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -274,6 +274,18 @@ ENDPROC(preserve_boot_args)
> * The dtb must be 8-byte aligned and live in the first 512M of memory.
> */
> __vet_fdt:
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + ldr x21, =_edata
> + add x21, x21, x28
> + ldr w0, [x21]
> +#ifndef __AARCH64EB__
> + ldr w1, =0xedfe0dd0 // FDT magic word
> +#else
> + ldr w1, =0xd00dfeed
> +#endif
> + cmp w0, w1
> + b.ne 1f // no FDT found
> +#endif
> tst x21, #0x7
> b.ne 1f
> cmp x21, x24
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index a2c2986..c71bac3 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -54,6 +54,18 @@ PECOFF_FILE_ALIGNMENT = 0x200;
> #define PECOFF_EDATA_PADDING
> #endif
>
> +/*
> + * Set FDT pointer 2MB aligned to ensure
> + * it don't cross a 2-megabyte boundary.
> + */
> +FDT_FILE_ALIGNMENT = (1 << 21);
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> +#define FDT_EDATA_PADDING \
> + .fdt_edata_padding : { BYTE(0); . = ALIGN(FDT_FILE_ALIGNMENT); }
> +#else
> +#define FDT_EDATA_PADDING
> +#endif
> +
> #ifdef CONFIG_DEBUG_ALIGN_RODATA
> #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
> #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
> @@ -149,8 +161,13 @@ SECTIONS
> _sdata = .;
> RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
> PECOFF_EDATA_PADDING
> + FDT_EDATA_PADDING /* 2MB aligned */
> _edata = .;
>
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + . += (1 << 21); /* maximum 2MB for FDT blob */
> +#endif
> +
> BSS_SECTION(0, 0, 0)
>
> . = ALIGN(PAGE_SIZE);
> --
> 1.8.0
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-06-04 9:35 [RFC PATCH] arm64: Image: Allow the appending of a device tree binary Yang Yingliang
2015-06-04 10:04 ` Mark Rutland
2015-06-04 10:07 ` Dave Martin
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