mobile-nixos · Jun 26, 2020 · Jun 26, 2020 · Jun 26, 2020 · Jun 27, 2020 · Jun 28, 2020
diff --git a/devices/xiaomi-begonia/README.adoc b/devices/xiaomi-begonia/README.adoc
@@ -0,0 +1,44 @@
+= Xiaomi Redmi Note 8 Pro
+include::_support/common.inc[]
+
+== Device-specific notes
+
+[NOTE]
+====
+*Do not acquire a Xiaomi Redmi Note 8 Pro with the intent to run Mobile NixOS
+on it.*
+
+This is *not* a recommended device.
+====
+
+It is of utmost importance that you read and familiarize yourself with
+link:https://forum.xda-developers.com/redmi-note-8-pro/how-to/guide-redmi-note-8-pro-megathread-t4056527/post82743009[
+the CFW megathread]. Not doing so *will result in a brick*.
+
+Again, *you will almost assuredly brick your phone* unless you read, understand
+and follow instructions pertaining to
+https://forum.xda-developers.com/redmi-note-8-pro/how-to/guide-redmi-note-8-pro-megathread-t4056527/post82743009#post82743009[
+the community CFW and the Redmi Note 8 Pro].
+
+Finally, as a last warning, you *will need* the 
+https://forum.xda-developers.com/redmi-note-8-pro/how-to/guide-redmi-note-8-pro-megathread-t4056527/post82743009#post82743009[
+community CFW for the Redmi Note 8 Pro].
+Otherwise *irrecoverably bricking is almost guaranteed*.
+
+
+=== Recovering from a brick, quick notes
+
+If you're told “Please select a valid authentication file or ask for
+help.” it may be a red herring _as long as you were mindful of not flashing a
+stock Xiaomi preloader and lk, and sticking to CFW_. Make sure you are *not*
+holding power or a volume key when you plug the device in.
+
+It is unknown what is necessary to be flashed using SP Flash Tool when
+recovering a bricked device. For some bricks it seems that flashing only `boot`
+is required. For other bricks it seems more is needed.
+
+
+=== Fastboot commands
+
+With the engineering preloader and aboot (lk), unknown for the stock Xiaomi
+one, it is not possible to `fastboot boot` a boot image.
diff --git a/devices/xiaomi-begonia/default.nix b/devices/xiaomi-begonia/default.nix
@@ -0,0 +1,61 @@
+{ config, lib, pkgs, ... }:
+
+{
+  mobile.device.name = "xiaomi-begonia";
+  mobile.device.identity = {
+    name = "Redmi Note 8 Pro";
+    manufacturer = "Xiaomi";
+  };
+
+  mobile.hardware = {
+    soc = "mediatek-mt6785";
+    # 4GB for the specific revision supported.
+    # When this will be actually used, this may be dropped to 3, and/or
+    # document all ram types as a list and work with min/max of those.
+    ram = 1024 * 6;
+    screen = {
+      width = 1080; height = 2340;
+    };
+  };
+
+  mobile.boot.stage-1 = {
+    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+  };
+
+  mobile.system.android = {
+    # This device adds skip_initramfs to cmdline for normal boots
+    boot_as_recovery = true;
+
+    # Though this device has "boot_as_recovery", it still has a classic
+    # recovery partition for recovery. Go figure.
+    has_recovery_partition = true;
+
+    bootimg.flash = {
+      offset_base = "0x40078000";
+      offset_kernel = "0x00008000";
+      offset_ramdisk = "0x07c08000";
+      offset_second = "0x00f00000";
+      offset_tags = "0x0bc08000";
+      pagesize = "2048";
+    };
+  };
+
+  mobile.system.vendor.partition = "/dev/disk/by-partlabel/vendor";
+
+  boot.kernelParams = [
+    # From TWRP CFW
+    "bootopt=64S3,32N2,64N2"
+    "androidboot.selinux=permissive"
+    #"buildvariant=eng"
+  ];
+
+  mobile.system.type = "android";
+
+  mobile.usb.mode = "gadgetfs";
+  # FIXME: attribute to sources.
+  mobile.usb.idVendor  = "2717"; # Xiaomi Communications Co., Ltd.
+  mobile.usb.idProduct = "FF80"; # Mi/Redmi series (RNDIS)
+
+  mobile.usb.gadgetfs.functions = {
+  };
+}
diff --git a/devices/xiaomi-begonia/kernel/0001-center-logo.patch b/devices/xiaomi-begonia/kernel/0001-center-logo.patch
@@ -0,0 +1,272 @@
+From 909ccff49e48c3c8765e4d9587af3ca40589c8ce Mon Sep 17 00:00:00 2001
+From: Peter Rosin <peda@axentia.se>
+Date: Mon, 26 Nov 2018 21:57:39 +0000
+Subject: [PATCH 1/4] fbdev: fbmem: make fb_show_logo_line return the end
+ instead of the height
+
+In preparation for allowing centering of the bootup logo, make
+fb_show_logo_line return where the next free framebuffer line is,
+instead of returning the height of the shown logo.
+
+Signed-off-by: Peter Rosin <peda@axentia.se>
+---
+ drivers/video/fbdev/core/fbmem.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
+index 138470409f49..064842afcd71 100644
+--- a/drivers/video/fbdev/core/fbmem.c
++++ b/drivers/video/fbdev/core/fbmem.c
+@@ -527,7 +527,7 @@ static int fb_show_logo_line(struct fb_info *info, int rotate,
+ 		info->pseudo_palette = saved_pseudo_palette;
+ 	kfree(logo_new);
+ 	kfree(logo_rotate);
+-	return logo->height;
++	return image.dy + logo->height;
+ }
+
+
+@@ -579,8 +579,8 @@ static int fb_show_extra_logos(struct fb_info *info, int y, int rotate)
+ 	unsigned int i;
+
+ 	for (i = 0; i < fb_logo_ex_num; i++)
+-		y += fb_show_logo_line(info, rotate,
+-				       fb_logo_ex[i].logo, y, fb_logo_ex[i].n);
++		y = fb_show_logo_line(info, rotate,
++				      fb_logo_ex[i].logo, y, fb_logo_ex[i].n);
+
+ 	return y;
+ }
+-- 
+2.25.3
+
+
+From b7e0e37a7ce12414f7fe465f9adb2ae2212998cb Mon Sep 17 00:00:00 2001
+From: Peter Rosin <peda@axentia.se>
+Date: Mon, 26 Nov 2018 21:57:41 +0000
+Subject: [PATCH 2/4] fbdev: fbmem: add config option to center the bootup logo
+
+If there are extra logos (CONFIG_FB_LOGO_EXTRA) the heights of these
+extra logos are not considered when centering the first logo vertically.
+
+Signed-off-by: Peter Rosin <peda@axentia.se>
+---
+ drivers/video/fbdev/core/fbmem.c | 25 ++++++++++++++++++++++++-
+ drivers/video/logo/Kconfig       |  9 +++++++++
+ 2 files changed, 33 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
+index 064842afcd71..176a61a46e02 100644
+--- a/drivers/video/fbdev/core/fbmem.c
++++ b/drivers/video/fbdev/core/fbmem.c
+@@ -508,8 +508,25 @@ static int fb_show_logo_line(struct fb_info *info, int rotate,
+ 		fb_set_logo(info, logo, logo_new, fb_logo.depth);
+ 	}
+
++#ifdef CONFIG_FB_LOGO_CENTER
++	{
++		int xres = info->var.xres;
++		int yres = info->var.yres;
++
++		if (rotate == FB_ROTATE_CW || rotate == FB_ROTATE_CCW) {
++			xres = info->var.yres;
++			yres = info->var.xres;
++		}
++
++		while (n && (n * (logo->width + 8) - 8 > xres))
++			--n;
++		image.dx = (xres - n * (logo->width + 8) - 8) / 2;
++		image.dy = y ?: (yres - logo->height) / 2;
++	}
++#else
+ 	image.dx = 0;
+ 	image.dy = y;
++#endif
+ 	image.width = logo->width;
+ 	image.height = logo->height;
+
+@@ -606,6 +623,7 @@ int fb_prepare_logo(struct fb_info *info, int rotate)
+ {
+ 	int depth = fb_get_color_depth(&info->var, &info->fix);
+ 	unsigned int yres;
++	int height;
+
+ 	memset(&fb_logo, 0, sizeof(struct logo_data));
+
+@@ -667,7 +685,12 @@ int fb_prepare_logo(struct fb_info *info, int rotate)
+  		}
+  	}
+
+-	return fb_prepare_extra_logos(info, fb_logo.logo->height, yres);
++	height = fb_logo.logo->height;
++#ifdef CONFIG_FB_LOGO_CENTER
++	height += (yres - fb_logo.logo->height) / 2;
++#endif
++
++	return fb_prepare_extra_logos(info, height, yres);
+ }
+
+ int fb_show_logo(struct fb_info *info, int rotate)
+diff --git a/drivers/video/logo/Kconfig b/drivers/video/logo/Kconfig
+index 0037104d66ac..3f4b5465afbc 100644
+--- a/drivers/video/logo/Kconfig
++++ b/drivers/video/logo/Kconfig
+@@ -10,6 +10,15 @@ menuconfig LOGO
+
+ if LOGO
+
++config FB_LOGO_CENTER
++	bool "Center the logo"
++	depends on FB=y
++	help
++	  When this option is selected, the bootup logo is centered both
++	  horizontally and vertically. If more than one logo is displayed
++	  due to multiple CPUs, the collected line of logos is centered
++	  as a whole.
++
+ config FB_LOGO_EXTRA
+ 	bool
+ 	depends on FB=y
+-- 
+2.25.3
+
+
+From df4d2a871da9f23eb57559cbd7778c7a6d0d76b8 Mon Sep 17 00:00:00 2001
+From: Peter Rosin <peda@axentia.se>
+Date: Mon, 7 Jan 2019 08:35:26 +0100
+Subject: [PATCH 3/4] fbdev: fbmem: convert CONFIG_FB_LOGO_CENTER into a cmd
+ line option
+
+A command line option is much more flexible than a config option and
+the supporting code is small. Gets rid of #ifdefs in the code too...
+
+Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
+Signed-off-by: Peter Rosin <peda@axentia.se>
+---
+ drivers/video/fbdev/core/fbmem.c | 19 ++++++++++---------
+ drivers/video/logo/Kconfig       |  9 ---------
+ include/linux/fb.h               |  1 +
+ 3 files changed, 11 insertions(+), 18 deletions(-)
+
+diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
+index 176a61a46e02..0fc6f30e9fde 100644
+--- a/drivers/video/fbdev/core/fbmem.c
++++ b/drivers/video/fbdev/core/fbmem.c
+@@ -53,6 +53,9 @@ EXPORT_SYMBOL(registered_fb);
+ int num_registered_fb __read_mostly;
+ EXPORT_SYMBOL(num_registered_fb);
+
++bool fb_center_logo __read_mostly;
++EXPORT_SYMBOL(fb_center_logo);
++
+ static struct fb_info *get_fb_info(unsigned int idx)
+ {
+ 	struct fb_info *fb_info;
+@@ -508,8 +511,7 @@ static int fb_show_logo_line(struct fb_info *info, int rotate,
+ 		fb_set_logo(info, logo, logo_new, fb_logo.depth);
+ 	}
+
+-#ifdef CONFIG_FB_LOGO_CENTER
+-	{
++	if (fb_center_logo) {
+ 		int xres = info->var.xres;
+ 		int yres = info->var.yres;
+
+@@ -522,11 +524,11 @@ static int fb_show_logo_line(struct fb_info *info, int rotate,
+ 			--n;
+ 		image.dx = (xres - n * (logo->width + 8) - 8) / 2;
+ 		image.dy = y ?: (yres - logo->height) / 2;
++	} else {
++		image.dx = 0;
++		image.dy = y;
+ 	}
+-#else
+-	image.dx = 0;
+-	image.dy = y;
+-#endif
++
+ 	image.width = logo->width;
+ 	image.height = logo->height;
+
+@@ -686,9 +688,8 @@ int fb_prepare_logo(struct fb_info *info, int rotate)
+  	}
+
+ 	height = fb_logo.logo->height;
+-#ifdef CONFIG_FB_LOGO_CENTER
+-	height += (yres - fb_logo.logo->height) / 2;
+-#endif
++	if (fb_center_logo)
++		height += (yres - fb_logo.logo->height) / 2;
+
+ 	return fb_prepare_extra_logos(info, height, yres);
+ }
+diff --git a/drivers/video/logo/Kconfig b/drivers/video/logo/Kconfig
+index 3f4b5465afbc..0037104d66ac 100644
+--- a/drivers/video/logo/Kconfig
++++ b/drivers/video/logo/Kconfig
+@@ -10,15 +10,6 @@ menuconfig LOGO
+
+ if LOGO
+
+-config FB_LOGO_CENTER
+-	bool "Center the logo"
+-	depends on FB=y
+-	help
+-	  When this option is selected, the bootup logo is centered both
+-	  horizontally and vertically. If more than one logo is displayed
+-	  due to multiple CPUs, the collected line of logos is centered
+-	  as a whole.
+-
+ config FB_LOGO_EXTRA
+ 	bool
+ 	depends on FB=y
+diff --git a/include/linux/fb.h b/include/linux/fb.h
+index 74063db2b193..d34433e08114 100644
+--- a/include/linux/fb.h
++++ b/include/linux/fb.h
+@@ -642,6 +642,7 @@ extern int fb_new_modelist(struct fb_info *info);
+
+ extern struct fb_info *registered_fb[FB_MAX];
+ extern int num_registered_fb;
++extern bool fb_center_logo;
+ extern struct class *fb_class;
+
+ extern int lock_fb_info(struct fb_info *info);
+-- 
+2.25.3
+
+
+From a4cfd195dc2bbcad6d0fbab07cea8072b1eda69c Mon Sep 17 00:00:00 2001
+From: Peter Rosin <peda@axentia.se>
+Date: Tue, 27 Aug 2019 11:09:26 +0000
+Subject: [PATCH 4/4] fbdev: fbmem: avoid exporting fb_center_logo
+
+The variable is only ever used from fbcon.c which is linked into the
+same module. Therefore, the export is not needed.
+
+Signed-off-by: Peter Rosin <peda@axentia.se>
+Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
+Cc: Jonathan Corbet <corbet@lwn.net>
+Cc: Matthew Wilcox <willy@infradead.org>
+Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
+Link: https://patchwork.freedesktop.org/patch/msgid/20190827110854.12574-4-peda@axentia.se
+(cherry picked from commit ab1c4c5e9d111a867964f4a67d9ab4a564d16b90)
+---
+ drivers/video/fbdev/core/fbmem.c | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
+index 0fc6f30e9fde..e169973e7f1d 100644
+--- a/drivers/video/fbdev/core/fbmem.c
++++ b/drivers/video/fbdev/core/fbmem.c
+@@ -54,7 +54,6 @@ int num_registered_fb __read_mostly;
+ EXPORT_SYMBOL(num_registered_fb);
+
+ bool fb_center_logo __read_mostly;
+-EXPORT_SYMBOL(fb_center_logo);
+
+ static struct fb_info *get_fb_info(unsigned int idx)
+ {
+-- 
+2.25.3
+
diff --git a/devices/xiaomi-begonia/kernel/0001-fix-teei-mediatek.patch b/devices/xiaomi-begonia/kernel/0001-fix-teei-mediatek.patch
@@ -0,0 +1,85 @@
+From 504a81eeb1c6578988758cc321a5e699f714363c Mon Sep 17 00:00:00 2001
+From: Samuel Dionne-Riel <samuel@dionne-riel.com>
+Date: Wed, 24 Jun 2020 15:32:04 -0400
+Subject: [PATCH 1/2] =?UTF-8?q?[HACK]=C2=A0Force=20teei=20paths=20into=20C?=
+ =?UTF-8?q?FLAGS?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+---
+ Makefile | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/Makefile b/Makefile
+index d106a749c74a..3ee3d2d34903 100644
+--- a/Makefile
++++ b/Makefile
+@@ -1859,3 +1859,10 @@ FORCE:
+ # Declare the contents of the .PHONY variable as phony.  We keep that
+ # information in a variable so we can use it in if_changed and friends.
+ .PHONY: $(PHONY)
++
++# What the heck mediatek...
++# The includes everywhere assume these folders are available. Mostly.
++# They are not.
++KBUILD_CFLAGS	+= -I$(srctree)/drivers/misc/mediatek/teei/300/common/include/
++KBUILD_CFLAGS	+= -I$(srctree)/drivers/misc/mediatek/teei/300/public/
++KBUILD_CFLAGS	+= -I$(srctree)/drivers/misc/mediatek/teei/300/tz_driver/include/
+-- 
+2.25.3
+
+
+From f51ca10bc5409859ab0de1547c7db67ccfe64eb7 Mon Sep 17 00:00:00 2001
+From: Samuel Dionne-Riel <samuel@dionne-riel.com>
+Date: Wed, 24 Jun 2020 15:32:23 -0400
+Subject: [PATCH 2/2] [HACK] teei header files are system headers
+
+---
+ drivers/misc/mediatek/cmdq/v3/cmdq_sec.c | 2 +-
+ drivers/misc/mediatek/m4u/2.4/m4u.c      | 2 +-
+ drivers/misc/mediatek/m4u/3.2/m4u.c      | 2 +-
+ 3 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/drivers/misc/mediatek/cmdq/v3/cmdq_sec.c b/drivers/misc/mediatek/cmdq/v3/cmdq_sec.c
+index 96c394d4552c..c41f6d53bc57 100644
+--- a/drivers/misc/mediatek/cmdq/v3/cmdq_sec.c
++++ b/drivers/misc/mediatek/cmdq/v3/cmdq_sec.c
+@@ -80,7 +80,7 @@ static struct list_head gCmdqSecContextList;
+ #include "cmdqsectl_api.h"
+
+ #if defined(CONFIG_MICROTRUST_TEE_SUPPORT)
+-#include "isee_kernel_api.h"
++#include <isee_kernel_api.h>
+ #endif
+
+ /* secure context to cmdqSecTL */
+diff --git a/drivers/misc/mediatek/m4u/2.4/m4u.c b/drivers/misc/mediatek/m4u/2.4/m4u.c
+index 770b6e5c8b06..805ee2aec64b 100644
+--- a/drivers/misc/mediatek/m4u/2.4/m4u.c
++++ b/drivers/misc/mediatek/m4u/2.4/m4u.c
+@@ -67,7 +67,7 @@
+
+
+ #if defined(CONFIG_MICROTRUST_TEE_SUPPORT)
+-#include "isee_kernel_api.h"
++#include <isee_kernel_api.h>
+ #define DRM_M4U_DRV_DRIVER_ID   (0x977aa)
+ #endif
+
+diff --git a/drivers/misc/mediatek/m4u/3.2/m4u.c b/drivers/misc/mediatek/m4u/3.2/m4u.c
+index c48cb65d0c87..349ed8e679f6 100644
+--- a/drivers/misc/mediatek/m4u/3.2/m4u.c
++++ b/drivers/misc/mediatek/m4u/3.2/m4u.c
+@@ -71,7 +71,7 @@
+
+
+ #if defined(CONFIG_MICROTRUST_TEE_SUPPORT)
+-#include "isee_kernel_api.h"
++#include <isee_kernel_api.h>
+ #define DRM_M4U_DRV_DRIVER_ID   (0x977aa)
+ #endif
+
+-- 
+2.25.3
+
diff --git a/devices/xiaomi-begonia/kernel/0001-mt6360-white-led-defaults-to-on.patch b/devices/xiaomi-begonia/kernel/0001-mt6360-white-led-defaults-to-on.patch
@@ -0,0 +1,25 @@
+From 7596d9c5fddf7b1fc81c24a5f71800d52af31527 Mon Sep 17 00:00:00 2001
+From: Samuel Dionne-Riel <samuel@dionne-riel.com>
+Date: Sat, 27 Jun 2020 21:24:22 -0400
+Subject: [PATCH] mt6360: white led defaults to on
+
+---
+ arch/arm64/boot/dts/mediatek/mt6360.dtsi | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arm64/boot/dts/mediatek/mt6360.dtsi b/arch/arm64/boot/dts/mediatek/mt6360.dtsi
+index 19bc396041e3..373c1687a06a 100644
+--- a/arch/arm64/boot/dts/mediatek/mt6360.dtsi
++++ b/arch/arm64/boot/dts/mediatek/mt6360.dtsi
+@@ -93,7 +93,7 @@
+ 			compatible = "mediatek,mt6360_pmu_rgbled";
+ 			mt,led_name = "white", "mt6360_pmu_led2",
+ 				      "mt6360_pmu_led3", "mt6360_pmu_led4";
+-			mt,led_default_trigger = "cc_mode", "cc_mode",
++			mt,led_default_trigger = "default-on", "cc_mode",
+ 						 "cc_mode", "none";
+ 		};
+ 		core {
+-- 
+2.25.4
+
diff --git a/devices/xiaomi-begonia/kernel/0001-mtkfb-Default-to-RGB-order.patch b/devices/xiaomi-begonia/kernel/0001-mtkfb-Default-to-RGB-order.patch
@@ -0,0 +1,26 @@
+From f096382e06d40cf2cf848ff9c62240fbb46a9976 Mon Sep 17 00:00:00 2001
+From: Samuel Dionne-Riel <samuel@dionne-riel.com>
+Date: Thu, 25 Jun 2020 23:53:54 -0400
+Subject: [PATCH] mtkfb: Default to RGB order
+
+The fine folks at Mediatek even left us an ifdef to use!
+---
+ drivers/misc/mediatek/video/mt6785/videox/mtkfb.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/misc/mediatek/video/mt6785/videox/mtkfb.c b/drivers/misc/mediatek/video/mt6785/videox/mtkfb.c
+index c02904908128..ea1a32736d46 100644
+--- a/drivers/misc/mediatek/video/mt6785/videox/mtkfb.c
++++ b/drivers/misc/mediatek/video/mt6785/videox/mtkfb.c
+@@ -2105,7 +2105,7 @@ static int mtkfb_fbinfo_init(struct fb_info *info)
+
+ 	var.transp.offset = 24;
+ 	var.red.length = 8;
+-#if 0
++#if 1
+ 	var.red.offset = 16;
+ 	var.red.length = 8;
+ 	var.green.offset = 8;
+-- 
+2.25.3
+
diff --git a/...ces/xiaomi-begonia/kernel/0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch b/...ces/xiaomi-begonia/kernel/0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
@@ -0,0 +1,79 @@
+From 5ce717535e07b8904a598dc93bc362abfe7453e6 Mon Sep 17 00:00:00 2001
+From: Alexey Min <alexey.min@gmail.com>
+Date: Wed, 11 Sep 2019 21:51:40 +0300
+Subject: [PATCH 3/3] arch: arm64: Add config option to fix bootloader cmdline
+ args
+
+Android bootloader passes some arguments in kernel command
+line, that make booting custom OSes harder:
+
+ * skip_initramfs
+ * root=PARTUUID=...
+ * init=/init
+
+Those parameters override default boot partition to hardcoded,
+set init binary to /init, disable booting from initramfs.
+
+If enabled, those parameters will be erased from bootloader's
+command line, and custom OS can boot the way it likes.
+---
+ arch/arm64/Kconfig | 17 +++++++++++++++++
+ drivers/of/fdt.c   | 14 ++++++++++++++
+ 2 files changed, 31 insertions(+)
+
+diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
+index 2829edba6aa5..bd9f05f83c7e 100644
+--- a/arch/arm64/Kconfig
++++ b/arch/arm64/Kconfig
+@@ -1125,6 +1125,23 @@ config CMDLINE_FORCE
+ 	  command-line options your boot loader passes to the kernel.
+ endchoice
+
++config CMDLINE_DROP_DANGEROUS_ANDROID_OPTIONS
++	bool "Drop certain dangerous options from cmdline"
++	default n
++	help
++	  Android bootloader passes some arguments in kernel command
++	  line, that make booting custom OSes harder:
++	  
++	    * skip_initramfs
++	    * root=PARTUUID=...
++	    * init=/init
++	  
++	  Those parameters override default boot partition to hardcoded,
++	  set init binary to /init, disable booting from initramfs.
++	  
++	  If enabled, those parameters will be erased from bootloader's
++	  command line, and custom OS can boot the way it likes.
++
+ config EFI_STUB
+ 	bool
+
+diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
+index ca175710c4c8..fd8257589648 100644
+--- a/drivers/of/fdt.c
++++ b/drivers/of/fdt.c
+@@ -1012,6 +1012,20 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
+
+ 	pr_debug("Command line is: %s\n", (char*)data);
+
++#ifdef CONFIG_CMDLINE_DROP_DANGEROUS_ANDROID_OPTIONS
++	pr_err("Replacing dangerous cmdline options...");
++	cmdline = strstr((const char *)data, "skip_initramfs");
++	if (cmdline)
++		*cmdline = '_';
++	cmdline = strstr((const char *)data, "root=");
++	if (cmdline)
++		*cmdline = '_';
++	cmdline = strstr((const char *)data, "init=");
++	if (cmdline)
++		*cmdline = '_';
++	pr_err("Command line now is: %s\n", (char*)data);
++#endif
++
+ 	/* break now */
+ 	return 1;
+ }
+-- 
+2.21.0
+
diff --git a/devices/xiaomi-begonia/kernel/config.aarch64 b/devices/xiaomi-begonia/kernel/config.aarch64
diff --git a/devices/xiaomi-begonia/kernel/default.nix b/devices/xiaomi-begonia/kernel/default.nix
@@ -0,0 +1,102 @@
+{
+  mobile-nixos
+, runCommand
+, fetchFromGitHub
+, kernelPatches ? [] # FIXME
+, buildPackages
+}:
+
+#
+# Some notes:
+#
+#  * https://github.com/MiCode/Xiaomi_Kernel_OpenSource/wiki/How-to-compile-kernel-standalone
+#
+# Things to note:
+#
+# This currently builds **only** with cross-compilation. That is going to stay
+# true until dtc_overlay's source is made available by OEMs.
+#
+# Either gcc49 or clang is needed for this kernel to build.
+#
+
+let
+  # The "main" CFW kernel repository
+  src = fetchFromGitHub {
+    owner = "AgentFabulous";
+    repo = "begonia";
+    rev = "186e9186f6fca7ca5aec11a0d967f5c525d56539";
+    sha256 = "1p08392pcavfjy5i0zc61dxibr0jq9kb3na1hdx85q0z3d9sfwp6";
+  };
+
+  inherit (buildPackages) dtc;
+
+  # This may seem weird, but doing this inside the kernel build breaks the binary.
+  # Note that `buildPackages.stdenv` is necessary since this is a tool for the host.
+  dtc_overlay = buildPackages.stdenv.mkDerivation {
+    name = "dtc_overlay-xiaomi-begonia";
+
+    nativeBuildInputs = with buildPackages; [
+      autoPatchelfHook
+      binutils
+    ];
+
+    inherit src;
+
+    buildPhase = ''
+      cp scripts/dtc/dtc_overlay ./
+      autoPatchelf dtc_overlay
+      ./dtc_overlay --version
+    '';
+
+    installPhase = ''
+      mv dtc_overlay $out
+    '';
+  };
+
+in
+(mobile-nixos.kernel-builder-clang_9 {
+  version = "4.14.184";
+  configfile = ./config.aarch64;
+
+  file = "Image.gz-dtb";
+  hasDTB = true;
+
+  inherit src;
+
+  patches = [
+    ./0001-mtkfb-Default-to-RGB-order.patch
+    ./0001-fix-teei-mediatek.patch
+    ./0001-center-logo.patch
+    ./0001-mt6360-white-led-defaults-to-on.patch
+    ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
+  ];
+
+  makeFlags = [
+    "DTC_EXT=${dtc}/bin/dtc"
+  ];
+
+  isModular = false;
+
+}).overrideAttrs({ postInstall ? "", postPatch ? [], ... }: {
+  installTargets = [
+    # uh, things seem screwey with that vendor kernel tree, and dependencies
+    # are not resolved as expected, so let's ask for the compressed kernel
+    # explictly first :/.
+    "Image.gz"
+    "zinstall"
+    "Image.gz-dtb"
+    "install"
+  ];
+
+  postInstall = postInstall + ''
+    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
+  '';
+
+  postPatch = postPatch + ''
+    echo ":: Replacing dtc_overaly"
+    (PS4=" $ "; set -x
+    rm scripts/dtc/dtc_overlay
+    cp ${dtc_overlay} scripts/dtc/dtc_overlay
+    )
+  '';
+})
diff --git a/modules/hardware-mediatek.nix b/modules/hardware-mediatek.nix
@@ -0,0 +1,23 @@
+{ config, lib, pkgs, ... }:
+
+let
+  inherit (lib) mkOption mkMerge mkIf types;
+  cfg = config.mobile.hardware.socs;
+in
+{
+  options.mobile = {
+    hardware.socs.mediatek-mt6785.enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = "enable when SOC is Mediatek MT6785 (Helio G90)";
+    };
+  };
+
+  config = mkMerge [
+    {
+      mobile = mkIf cfg.mediatek-mt6785.enable {
+        system.system = "aarch64-linux";
+      };
+    }
+  ];
+}
diff --git a/modules/module-list.nix b/modules/module-list.nix
@@ -9,6 +9,7 @@
   ./generated-filesystems.nix
   ./hardware-allwinner.nix
   ./hardware-generic.nix
+  ./hardware-mediatek.nix
   ./hardware-qualcomm.nix
   ./hardware-ram.nix
   ./hardware-rockchip.nix

diff --git a/overlay/mkbootimg/default.nix b/overlay/mkbootimg/default.nix
@@ -1,27 +1,14 @@
 {stdenv, fetchurl}:
 
-let
-  version = "2019.04.13";
-in
-# https://github.com/osm0sis/mkbootimg/blob/2017.12.13/bootimg.h
-# This builds the MSM-specific bootimgs...
-# This is... not entirely bad, but not good either.
-# We will probably need to make it available as msm-mkbootimg...
-# MAIN difference is this:
-#  * https://github.com/osm0sis/mkbootimg/blob/015be7ed1001f60c9d621970cab71577d396f452/bootimg.h#L46
-# This is in place of the `uint32_t header_version` field.
-stdenv.mkDerivation {
-  inherit version;
-  name = "mkbootimg";
+stdenv.mkDerivation rec {
+  pname = "mkbootimg";
+  version = "2020.05.18";
 
   src = fetchurl {
     url = "https://github.com/osm0sis/mkbootimg/archive/${version}.tar.gz";
-    sha256 = "0pwxc1wn38a159lcwlsri4dc8b7kpnfyryi2l75i4a61wxqb94kj";
+    sha256 = "1zz06x31rak9sv5v01kj3cvqvzh5qvq34p00paw5p3jl0lxvnvwc";
   };
 
-  postPatch = ''
-  '';
-
   installPhase = ''
     mkdir -p $out/bin
     cp -v mkbootimg $out/bin/
@@ -32,6 +19,4 @@ stdenv.mkDerivation {
   NIX_CFLAGS_COMPILE = [
     "-Wno-error=address-of-packed-member"
   ];
-
-  # TODO meta url : https://source.codeaurora.org/quic/kernel/skales/plain/dtbTool
 }
diff --git a/overlay/overlay.nix b/overlay/overlay.nix
@@ -101,6 +101,9 @@ in
       kernel-builder-gcc6 = callPackage ./mobile-nixos/kernel/builder.nix {
         stdenv = with self; overrideCC stdenv buildPackages.gcc6;
       };
+      kernel-builder-clang_9 = callPackage ./mobile-nixos/kernel/builder.nix {
+        stdenv = with self; overrideCC stdenv buildPackages.clang_9;
+      };
 
       stage-1 = {
         script-loader = callPackage ../boot/script-loader {};