RFC : mmc : boot partition is set as a read-write.

RFC : mmc : boot partition is set as a read-write.

[NamJae Jeon]

mmc : boot partition is set as a read-write.

There is a case that user directly update boot partition through mmcblk0boot0,1.
However, the current boot partition is set as a read-only.
I suggest that boot partition is set as a read-write if there is no
reason that it should be read-only.

static int mmc_blk_alloc_parts(struct mmc_card *card, struct mmc_blk_data *md)
{
	int ret = 0;

	if (!mmc_card_mmc(card))
		return 0;

	if (card->ext_csd.boot_size) {
		ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT0,
					 card->ext_csd.boot_size >> 9,
					 false,
					 "boot0");
		if (ret)
			return ret;
		ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT1,
					 card->ext_csd.boot_size >> 9,
					 false,
					 "boot1");
		if (ret)
			return ret;
	}
}

Thanks.

Re: RFC : mmc : boot partition is set as a read-write.

[Chris Ball]

Hi,

On Sun, Sep 18 2011, NamJae Jeon wrote:
> mmc : boot partition is set as a read-write.
>
> There is a case that user directly update boot partition through mmcblk0boot0,1.
> However, the current boot partition is set as a read-only.
> I suggest that boot partition is set as a read-write if there is no
> reason that it should be read-only.

There is a reason.

Documentation/mmc/mmc-dev-parts.txt:

MMC Boot Partitions
===================

Read and write access is provided to the two MMC boot partitions. Due to
the sensitive nature of the boot partition contents, which often store
a bootloader or bootloader configuration tables crucial to booting the
platform, write access is disabled by default to reduce the chance of
accidental bricking.

To enable write access to /dev/mmcblkXbootY, disable the forced read-only
access with:

echo 0 > /sys/block/mmcblkXbootY/force_ro

==
- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child

Re: RFC : mmc : boot partition is set as a read-write.

[NamJae Jeon]

2011/9/19 Chris Ball <cjb@laptop.org>:
> Hi,
>
> On Sun, Sep 18 2011, NamJae Jeon wrote:
>> mmc : boot partition is set as a read-write.
>>
>> There is a case that user directly update boot partition through mmcblk0boot0,1.
>> However, the current boot partition is set as a read-only.
>> I suggest that boot partition is set as a read-write if there is no
>> reason that it should be read-only.
>
> There is a reason.
>
> Documentation/mmc/mmc-dev-parts.txt:
>
> MMC Boot Partitions
> ===================
>
> Read and write access is provided to the two MMC boot partitions. Due to
> the sensitive nature of the boot partition contents, which often store
> a bootloader or bootloader configuration tables crucial to booting the
> platform, write access is disabled by default to reduce the chance of
> accidental bricking.
>
> To enable write access to /dev/mmcblkXbootY, disable the forced read-only
> access with:
>
> echo 0 > /sys/block/mmcblkXbootY/force_ro
>
> ==
> - Chris.
> --
> Chris Ball   <cjb@laptop.org>   <http://printf.net/>
> One Laptop Per Child
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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>

Hi. Chris.

There is the way you are.

Thanks a lot.