[PATCH] mkimage: sunxi_egon: Allow overriding the padding size

[PATCH] mkimage: sunxi_egon: Allow overriding the padding size

[Samuel Holland]

Due to a bug in the H3 SoC, where the CPU 0 hotplug flag cannot be
written, resuming CPU 0 requires using the "Super Standby" code path in
the BROM instead of the hotplug path. This path requires jumping to an
eGON image in SRAM.

This resume image, whose single purpose is to jump back to the secure
monitor, only needs to contain a single instruction. Padding the image
to 8 KiB would be wasteful of SRAM. Hook up the -B (block size) option
so users can set the block/padding size.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---

 tools/sunxi_egon.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/sunxi_egon.c b/tools/sunxi_egon.c
index a5299eb6a1..d1398c07fb 100644
--- a/tools/sunxi_egon.c
+++ b/tools/sunxi_egon.c
@@ -10,9 +10,10 @@
 
 /*
  * NAND requires 8K padding. SD/eMMC gets away with 512 bytes,
- * but let's use the larger padding to cover both.
+ * but let's use the larger padding by default to cover both.
  */
 #define PAD_SIZE			8192
+#define PAD_SIZE_MIN			512
 
 static int egon_check_params(struct image_tool_params *params)
 {
@@ -114,10 +115,12 @@ static int egon_check_image_type(uint8_t type)
 static int egon_vrec_header(struct image_tool_params *params,
 			    struct image_type_params *tparams)
 {
+	int pad_size = ALIGN(params->bl_len ?: PAD_SIZE, PAD_SIZE_MIN);
+
 	tparams->hdr = calloc(sizeof(struct boot_file_head), 1);
 
-	/* Return padding to 8K blocks. */
-	return ALIGN(params->file_size, PAD_SIZE) - params->file_size;
+	/* Return padding to complete blocks. */
+	return ALIGN(params->file_size, pad_size) - params->file_size;
 }
 
 U_BOOT_IMAGE_TYPE(
-- 
2.32.0

Re: [PATCH] mkimage: sunxi_egon: Allow overriding the padding size

[Andre Przywara]

On Tue, 12 Oct 2021 19:21:27 -0500
Samuel Holland <samuel@sholland.org> wrote:

> Due to a bug in the H3 SoC, where the CPU 0 hotplug flag cannot be
> written, resuming CPU 0 requires using the "Super Standby" code path in
> the BROM instead of the hotplug path. This path requires jumping to an
> eGON image in SRAM.
> 
> This resume image, whose single purpose is to jump back to the secure
> monitor, only needs to contain a single instruction. Padding the image
> to 8 KiB would be wasteful of SRAM. Hook up the -B (block size) option
> so users can set the block/padding size.

I like that one, I always got annoyed about this rather large fixed
padding size, even though the vast majority of users don't need it.

Also the default behaviour is unchanged, so little risk here.

> Signed-off-by: Samuel Holland <samuel@sholland.org>

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

Cheers,
Andre

> ---
> 
>  tools/sunxi_egon.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/sunxi_egon.c b/tools/sunxi_egon.c
> index a5299eb6a1..d1398c07fb 100644
> --- a/tools/sunxi_egon.c
> +++ b/tools/sunxi_egon.c
> @@ -10,9 +10,10 @@
>  
>  /*
>   * NAND requires 8K padding. SD/eMMC gets away with 512 bytes,
> - * but let's use the larger padding to cover both.
> + * but let's use the larger padding by default to cover both.
>   */
>  #define PAD_SIZE			8192
> +#define PAD_SIZE_MIN			512
>  
>  static int egon_check_params(struct image_tool_params *params)
>  {
> @@ -114,10 +115,12 @@ static int egon_check_image_type(uint8_t type)
>  static int egon_vrec_header(struct image_tool_params *params,
>  			    struct image_type_params *tparams)
>  {
> +	int pad_size = ALIGN(params->bl_len ?: PAD_SIZE, PAD_SIZE_MIN);
> +
>  	tparams->hdr = calloc(sizeof(struct boot_file_head), 1);
>  
> -	/* Return padding to 8K blocks. */
> -	return ALIGN(params->file_size, PAD_SIZE) - params->file_size;
> +	/* Return padding to complete blocks. */
> +	return ALIGN(params->file_size, pad_size) - params->file_size;
>  }
>  
>  U_BOOT_IMAGE_TYPE(