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Re: How to receive notification of a new (disk) device being connected?
From: |
Andrei Borzenkov |
Subject: |
Re: How to receive notification of a new (disk) device being connected? |
Date: |
Thu, 28 Apr 2016 20:55:12 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 |
28.04.2016 16:03, TJ пишет:
> I'm currently finalising a patch that adds key-file support to
> cryptodisk::cryptomount and luks.
>
> As well as being able to grub_device_iterate(hook,...) to search the
> existing devices for the key-file the code needs to wait for TIMEOUT
> seconds for additional (usually USB Mass Storage) devices to be
> connected and when they are search them for the key-file.
>
> Is there an existing mechanism to receive such notifications, or a
> blocking call that returns if a device is connected or a timeout is hit?
>
No. GRUB depends on firmware for disk access and not every firmware
supports hotplugging in the first place.
> Otherwise it looks like I'll have to track which devices are connected
> when the TIMEOUT loop is first entered, grub_sleep(), then
> grub_device_iterate() and see if the device list has any new entries.
>
> Secondly: am I correct to think using grub_search_fs_file(keyfile_name,
> variable_name, ...) is the correct way to search for the key-file across
> all devices, or do I need to use a specific hint type to indicate all
> devices should be searched?
>
Hints are used to optimize search - if you can guess firmware device
name, you avoid need to search across all devices. But it is in no way
mandatory, and search should work without it.