From c6722b86bfb34159c130606ff2ce46ef741c3b17 Mon Sep 17 00:00:00 2001
From: Niklaus Giger <niklaus.giger@member.fsf.org>
Date: Mon, 23 Mar 2020 20:19:54 +0100
Subject: Document librem laptop 15v3

---
 README.md                    |  2 +-
 purism/librem/13v3/README.md | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 8567028..1d9234f 100644
--- a/README.md
+++ b/README.md
@@ -73,7 +73,7 @@ See code for all available configurations.
 | PC Engines APU                    | `<nixos-hardware/pcengines/apu>`                   |
 | [Raspberry Pi 2][]                | `<nixos-hardware/raspberry-pi/2>`                  |
 | [Samsung Series 9 NP900X3C][]     | `<nixos-hardware/samsung/np900x3c>`                |
-| [Purism Librem 13v3][]            | `<nixos-hardware/purism/librem/13v3>`              |
+| [Purism Librem 13v3/15v3][]       | `<nixos-hardware/purism/librem/13v3>`              |
 | Supermicro A1SRi-2758F            | `<nixos-hardware/supermicro/a1sri-2758f>`          |
 | Supermicro X10SLL-F               | `<nixos-hardware/supermicro/x10sll-f>`             |
 | [Toshiba Chromebook 2 `swanky`][] | `<nixos-hardware/toshiba/swanky>`                  |
diff --git a/purism/librem/13v3/README.md b/purism/librem/13v3/README.md
index 8009eb3..2ecb6bd 100644
--- a/purism/librem/13v3/README.md
+++ b/purism/librem/13v3/README.md
@@ -1,3 +1,6 @@
+This config is for [Librem 13v3](https://puri.sm/products/librem-13/) and [15v3](https://puri.sm/products/librem-15/) Laptops from Purism.
+
+
 Librem comes with Coreboot + SeaBIOS payload. That means EFI boot is not
 possible. Use `fdisk` to partition hard drive, and GRUB as a bootloader:
 
@@ -10,3 +13,40 @@ possible. Use `fdisk` to partition hard drive, and GRUB as a bootloader:
   };
 }
 ```
+
+## Adding a PureOS partition to the GRUB menu
+
+I first assume that `boot.loader.grub.useOSProber = true;` should be sufficient.
+However GRUB was not able to identify the disks correctly and it took me several
+reinstallation till setting `boot.loader.grub.fsIdentifier= "provided";` and using
+boot.loader.grub.extraEntries allowed me to dual boot NixOS and PureOS.
+
+Be aware that each time the PureOS updates the /boot/grub/grub.cfg you will be unable
+to boot into NixOS unless you patch grub.cfg manually again.
+
+Therefore: If you want to be able to boot into your old PureOS distribution
+add the following lines, assuming that you have a separate boot partition
+Adapt linux version and the UUID to your disk!!
+
+
+```nix
+{
+  boot.loader.grub.useOSProber = false;
+  boot.loader.grub.fsIdentifier= "provided";
+  boot.loader.grub.extraEntries = ''
+  menuentry "PureOS with linux 4.19.0-5-amd64 on /dev/sdb2 " {
+      insmod gzio
+      if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
+      insmod part_msdos
+      insmod ext2
+      set root='hd0,msdos1'
+      if [ x$feature_platform_search_hint = xy ]; then
+        search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1  ef7a4dcf-8cc4-4870-b860-3ed64906f9b9
+      else
+        search --no-floppy --fs-uuid --set=root ef7a4dcf-8cc4-4870-b860-3ed64906f9b9
+      fi
+      linux   /vmlinuz-4.19.0-5-amd64 root=UUID=43899f26-04f2-4ccb-b52a-c9441f1a1a6d ro  quiet splash resume=UUID=923317f8-d8bb-4e1f-bca3-f36a556de609 # $vt_handoff
+      initrd  /initrd.img-4.19.0-5-amd64
+  };
+}
+```
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