24.02.2020 20:23, Dmitry Osipenko пишет: > 24.02.2020 19:33, Karel Zak пишет: >> On Wed, Feb 19, 2020 at 09:59:54AM -0700, Stephen Warren wrote: >>> On 2/19/20 9:27 AM, Christoph Hellwig wrote: >>>> On Wed, Feb 19, 2020 at 07:23:39PM +0300, Dmitry Osipenko wrote: >>>>> The gpt_sector=<sector> causes the GPT partition search to look at the >>>>> specified sector for a valid GPT header if the GPT is not found at the >>>>> beginning or the end of block device. >>>>> >>>>> In particular this is needed for NVIDIA Tegra consumer-grade Android >>>>> devices in order to make them usable with the upstream kernel because >>>>> these devices use a proprietary / closed-source partition table format >>>>> for the EMMC and it's impossible to change the partition's format. Luckily >>>>> there is a GPT table in addition to the proprietary table, which is placed >>>>> in uncommon location of the EMMC storage and bootloader passes the >>>>> location to kernel using "gpt gpt_sector=<sector>" cmdline parameters. >>>>> >>>>> This patch is based on the original work done by Colin Cross for the >>>>> downstream Android kernel. >>>> >>>> I don't think a magic command line is the way to go. The best would be >>>> to reverse-engineer the proprietary partition table format. If that is >>>> too hard we can at least key off the odd GPT location based of it's >>>> magic number. >> >> +1 >> >>> I thought that the backup GPT was always present in the standard location; >> >> If they have proprietary stuff on begin of the device and valid backup >> GPT at the end of the device then designer of this junk is crazy, because >> many GPT fdisk-like tools will try to recover from the backup header and >> overwrite the unknown (invalid) stuff at the begin of the device... > > It's a problem created by vendor, but these devices are assumed to run > Android-only. So it's not really that bad :) > Is there any way to mark parts of block device as read-only? Such that userspace couldn't write to the RO-marked sectors, I guess that could help to save someone's bacon.
