If you've installed successfully in legacy mode but had to change some kernel parameters for it to work, you should try installing in UEFI mode with the same parameters.
**Change xen configuration directly in an iso image**
01. Get EFI partition boundaries `parted Qubes-R4.0-rc4-x86_64.iso unit B print`
02. Using the start address and the size of the EFI partition, setup a loop device for it `sudo losetup -o 524288 --sizelimit 30562304 /dev/loop0 Qubes-R4.0-rc4-x86_64.iso`
03. Mount the loop device `sudo mount /dev/loop0 /mnt`
04. Edit `EFI/BOOT/BOOTX64.cfg` to add your params to the `kernel` configuration key
05. Save your changes, unmount and dd to usb device
1. Follow the [steps here](/doc/uefi-troubleshooting/#successfully-installed-in-legacy-mode-but-had-to-change-some-kernel-parameters) to edit the `[qubes-verbose]` section of your installer's `BOOTX64.cfg`.
2. Boot the installer and continue to install as normal, but don't reboot the system at the end when prompted.
3. Go to `tty2` (Ctrl-Alt-F2).
4. Use your preferred text editor (`nano` works) to edit `/mnt/sysimage/boot/efi/EFI/qubes/xen.cfg`, verifying the `noexitboot` and `mapbs` lines are not present.
This is also a good time to make permanent any other changes needed to get the installer to work, such as `nouveau.modeset=0`.
### Changing `options=console=` parameter to `none` ###
If removing `noexitboot` and `mapbs` did not help, you can try changing the `options=console=` parameter to `none`. The detailed solution can be found in the comments of [this GitHub issue](https://github.com/QubesOS/qubes-issues/issues/5383)
1. Follow the [steps here](/doc/uefi-troubleshooting/#successfully-installed-in-legacy-mode-but-had-to-change-some-kernel-parameters) to edit the `[qubes-verbose]` section of your installer's `BOOTX64.cfg`.
1. Follow the [steps here](/doc/uefi-troubleshooting/#successfully-installed-in-legacy-mode-but-had-to-change-some-kernel-parameters) to edit the `[qubes-verbose]` section of your installer's `xen.cfg`.
2. Boot the installer and continue to install as normal, until towards the end when you will receive a warning about being unable to create the EFI boot entry.
Click continue, but don't reboot the system at the end when prompted.
3. Go to `tty2` (Ctrl-Alt-F2).
4. Use your preferred text editor (`nano` works) to edit `/mnt/sysimage/boot/efi/EFI/qubes/xen.cfg`, adding the `efi=no-rs` option to the end of the `options=` line.
Whenever there is a kernel or Xen update for Qubes, you will need to follow [these steps](/doc/uefi-troubleshooting/#boot-device-not-recognized-after-installing) because your system is using the fallback UEFI bootloader in `[...]/EFI/BOOT` instead of directly booting to the Qubes entry under `[...]/EFI/qubes`.
Some laptops cannot read from an external boot device larger than 8GB. If you encounter a black screen when performing an installation from a USB stick, ensure you are using a USB drive less than 8GB, or a partition on that USB lesser than 8GB and of format FAT32.
There is a [common bug in UEFI implementation](http://xen.markmail.org/message/f6lx2ab4o2fch35r) affecting mostly Lenovo systems, but probably some others too.
While some systems need `mapbs` and/or `noexitboot` disabled to boot, others require them enabled at all times.
Although these are enabled by default in the installer, they are disabled after the first stage of a successful install.
You can re-enable them either as part of the install process:
1. Copy the `/boot/efi/EFI/qubes/` directory to `/boot/efi/EFI/BOOT/` (the contents of `/boot/efi/EFI/BOOT` should be identical to `/boot/efi/EFI/qubes` besides what is described in steps 2 and 3):
In some cases installer fails to finish EFI setup and leave the system without a Qubes-specific EFI configuration.
In such a case you need to finish those parts manually.
You can do that just after installation (switch to `tty2` with Ctrl-Alt-F2), or by booting from installation media in [rescue mode](/doc/uefi-troubleshooting/#accessing-installer-rescue-mode-on-uefi).
