[arch-general] How to install archlinux using a specific parition of usb instead of the whole usb?

[Hongyi Zhao]

Hi,

I try to use a specific partition of usb to install archlinux, the
following is the step:

Suppose the /dev/sdc is my usb:

$ sudo ddrescue -f archlinux-2019.11.01-x86_64.iso /dev/sdc2

Then I reboot my computer with the grub standalone bootloader and from
within the command line of grub, I do the following:

Suppose the (hd2,2) is the partition which corresponding to the
/dev/sdc2, then I run the following   commands:

grub> set root=hd2,2
grub> chainloader /EFI/boot/bootx64.efi
grub> boot

But, the above step failed to boot, with the error similar to this in my ming:

Failed to find the loader.efi

OTOH, if I dd'ed the arch iso onto the whole usb disk like the following:

$ sudo ddrescue -f archlinux-2019.11.01-x86_64.iso /dev/sdc

Then, it will be successfully booted into the installation menu of
archlinux.  So I want to know whether is is possible for me to use a
specific partition of usb instead of the whole usb disk for
installation archlinux?

Regards
-- 
Hongsheng Zhao <hongyi.zhao at gmail.com>
Institute of Semiconductors, Chinese Academy of Sciences
GnuPG DSA: 0xD108493