Re: [orca-list] is it possible to boot latest Ubuntu by using SDC cart?

[Didier Spaier <didier slint fr>]

Hello,

I can't answer specifically for Ubuntu or Debian, but will provide some generic information.

1. Grub2 should be able to install on a SD card, provided that the installer  knows about the naming scheme 
of the device.
I case of SD card is is something like /dev/mmcblk<number> so you'd just write e.g. grub-install 
/dev/mmbcblk0 from an installed system

Similarly the ESP should be a partition of the SD card, like e.g. mmcblk0p1.
Provided that this partition be mounted as /boot/efi in the to-be-installed system, and its root partition be 
mounted as /mnt during installation, you could install grub with a command like:
chroot /mnt grub-install --target=x86_64-efi /dev/mmcblk0
For this to work you need to have mounted the ESP e.g. /dev/mmcblk0p1 as /mnt/boot/efi and bind mounted /dev 
/proc and /sys as /mnt/dev, /mnt/proc and /mnt/sys respectively.

If you intend to make this system "portable" (in case you use an USB card reader), use also the option 
--removable and --no-nvram of grub-install.

I know nothing about petitboot.

About the support by the kernel of an eMMC device, you will need at least the mmc, mmc_block and mmc_core 
drivers either built in the kernel or shipped in an initrd as modules.

Whether this condition be met depends on how the kernel you install has been configured.

I strongly advise against using an ext file system because, yes, your device will then quickly wear out, even 
with ext2 that doesn't write a journal on the device

The best file system for SD card (and USB sticks) is F2FS, but is not provided in the default grub 2.02 (will 
be in grub2 2.04). however maybe the grub provided by your distribution provides it.

You can check looking in /usr/lib/grub/x86_64-efi: if there is file named f2fs.module there, the answer is 
yes.

HTH.

Best,

Didier


On 05/05/2019 11:21, Mgr. Janusz Chmiel via orca-list wrote:
> I have very specific question.
> Is it possible to boot latest Ubuntu 64 bit edition from SDC cart which can be connected by using
> 1. internal SD cart reader
> 2. Or it can be also connected by external USB card reader.
> Sure, I Am aware, that standard GRUB compatible with EFI can not communicate with USB or internal SD card 
> reader. So I have other idea.
> What about using
> petitboot.
> It is possible to use it to perform accessible boot screen for Debian operating system. So what about 
> configuring kernel boot option to support SD cart?
> Or I will get many kernel warnings when I will try to boot from this device? Is Linux kernel programmed so 
> it can boot from this device?
> Or can I simply install Ubuntu to SD card and I can use USB card reader to access data? May be, that EFI 
> boot from Windows 10 can support some USB devices even on boot time, because USB flash drives and USB 
> external harddisks are supported.
> But there is other performance problem.
> I AM afraid, that when I will use USB card reader, The performance will be much more slower than when using 
> internal SDcard reader. But I think, that I do not have much chances to force EFI driving program or Boot 
> manager for Windows 10 to support this device to directly boot from SD card.
> Sure, I will disable swap file support to prevent card over-burning. May be, that somebody of us also know 
> about some EXT file system optimisation command line commands to make those devices working fast. I think, 
> that default EXT4 with journalling support is may be not very good for SD card.
> Should I rather use EXT2?
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