From: Karel Zak <kzak@redhat.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: "Christoph Hellwig" <hch@infradead.org>,
"Dmitry Osipenko" <digetx@gmail.com>,
"Jens Axboe" <axboe@kernel.dk>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"Colin Cross" <ccross@android.com>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Jonathan Hunter" <jonathanh@nvidia.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"David Heidelberg" <david@ixit.cz>,
"Peter Geis" <pgwipeout@gmail.com>,
linux-efi@vger.kernel.org, linux-tegra@vger.kernel.org,
linux-block@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] partitions/efi: Add 'gpt_sector' kernel cmdline parameter
Date: Mon, 24 Feb 2020 17:33:42 +0100 [thread overview]
Message-ID: <20200224163342.d4acf224b56celup@ws.net.home> (raw)
In-Reply-To: <f9e41108-7811-0deb-6977-be0f60e23b52@wwwdotorg.org>
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...
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
next prev parent reply other threads:[~2020-02-24 16:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-19 16:23 [PATCH v1] partitions/efi: Add 'gpt_sector' kernel cmdline parameter Dmitry Osipenko
2020-02-19 16:26 ` Ard Biesheuvel
2020-02-19 16:36 ` Dmitry Osipenko
2020-02-19 16:27 ` Christoph Hellwig
2020-02-19 16:38 ` Dmitry Osipenko
2020-02-19 16:59 ` Stephen Warren
2020-02-19 17:44 ` Dmitry Osipenko
2020-02-24 16:33 ` Karel Zak [this message]
2020-02-24 17:23 ` Dmitry Osipenko
2020-02-24 18:22 ` Dmitry Osipenko
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