Siarhei Siamashka siarhei.siamashka@gmail.com writes:
On Tue, 01 May 2018 18:25:06 +0100 Måns Rullgård mans@mansr.com wrote:
Maxime Ripard maxime.ripard@free-electrons.com writes:
The U-Boot binary may trip over its actual allocated size in the storage. In such a case, the environment will not be readable anymore (because corrupted when the new image was flashed), and any attempt at using saveenv to reconstruct the environment will result in a corrupted U-Boot binary.
Reviewed-by: Andre Przywara andre.przywara@arm.com Signed-off-by: Maxime Ripard maxime.ripard@free-electrons.com
arch/arm/dts/sunxi-u-boot.dtsi | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/arch/arm/dts/sunxi-u-boot.dtsi b/arch/arm/dts/sunxi-u-boot.dtsi index 5adfd9bca2ec..72e95afd780e 100644 --- a/arch/arm/dts/sunxi-u-boot.dtsi +++ b/arch/arm/dts/sunxi-u-boot.dtsi @@ -1,5 +1,14 @@ #include <config.h>
+/*
- This is the maximum size the U-Boot binary can be, which is basically
- the start of the environment, minus the start of the U-Boot binary in
- the MMC. This makes the assumption that the MMC is using 512-bytes
- blocks, but devices using something other than that remains to be
- seen.
- */
+#define UBOOT_MMC_MAX_SIZE (CONFIG_ENV_OFFSET - (CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR * 512))
/ { binman { filename = "u-boot-sunxi-with-spl.bin"; @@ -8,6 +17,9 @@ filename = "spl/sunxi-spl.bin"; }; u-boot-img { +#ifdef CONFIG_MMC
size = <UBOOT_MMC_MAX_SIZE>;+#endif pos = <CONFIG_SPL_PAD_TO>; }; }; --
This is broken in (at least) two ways:
It is simply nonsensical if u-boot and env are on different devices or not on mmc even if mmc support is enabled.
It causes u-boot-sunxi-with-spl.bin to be padded to the env offset. At best, this is useless. If the env doesn't immediately follow u-boot, it really breaks things.
Please fix or revert, I don't really care which.
The padding is not useless. It reserves space for future size expansions and makes it harder for the users to hurt themselves.
For example, if the padded U-Boot size is 1024K while the actual size is only ~800K, then adventurous users might be tempted to fit some of their data into this gap. Yay, ~200K of storage space for free! Except that the next U-Boot release may grow up to 900K without any warning and if the users are not careful enough, then their data would be corrupted during upgrade.
Do U-Boot users really need that level of hand-holding?
Could you please tell us what is your problem and why reverting this patch would fix it?
See above. Best case, it just wastes space in the created file. If the configuration is anything other than U-Boot immediately followed by env on the same device, it _will_ break things horribly. A few examples:
1. U-Boot and env are on different devices, e.g. U-Boot on mmc and env in SPI NOR flash. In this case, padding the file to the env offset makes no sense. Writing the image will corrupt anything stored after U-Boot at a smaller (but still safe) offset.
2. U-Boot at a non-zero offset, followed by env, but _not_ on mmc. If CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, probably at its default value, is smaller than the offset of U-Boot in its actual device, the padding will be too large. Writing the image file will then corrupt a stored env.
3. U-Boot at start of device, env at end as indicated by a negative CONFIG_ENV_OFFSET. With this configuration, binman tries to pad the image to (nearly) 2^64 bytes and promptly fills up your storage device.
I keep running into variants of these, and I'm weary of it.