Re: How to boot FreeBSD for arm 32 bit as DomU with u-boot on my ARM Chromebook

From: Mario Marietto <marietto2008_at_gmail.com>
Date: Tue, 19 Dec 2023 17:07:40 UTC
....I see that some other interesting files have been produced by u-boot
when I have compiled it :

u-boot
u-boot.lds
u-boot.bin
u-boot.map
u-boot-nodtb.bin
u-boot.dtb
u-boot.srec
u-boot-dtb.bin
u-boot.sym

So,maybe I should use a different u-boot* file for booting FreeBSD ?


On Tue, Dec 19, 2023 at 4:28 PM Mario Marietto <marietto2008@gmail.com>
wrote:

> Hello to everyone.
>
> I have compiled the needed u-boot.bin from scratch using this procedure :
>
> # git clone https://github.com/u-boot/u-boot.git
> # cd u-boot
> # ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- make snow_defconfig : this
> line generates the file .config
> # nano .config and I've added these parameters :
>
> CONFIG_ARMV7_NONSEC=n
> CONFIG_EFI_GRUB_ARM32_WORKAROUND=y
>
> the uboot-bin file is generated with this command :
>
> # ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- make
>
> At this point,I took a look inside the .config file and I saw that the
> parameter "CONFIG_ARMV7_NONSEC=n" has been removed. So,for some reason,it
> is not accepted and this could be a problem....
>
> These are the xen config files that I've used :
>
> nano freebsd.cfg
>
> name="test"
> kernel="u-boot.bin"
> extra = "console=hvc0"
> memory=256
> vcpus=1
> disk = [ 'FreeBSD-13.2-RELEASE-armv7.img,raw,xvda' ]
>
> nano start-freebsd
>
> xl create freebsd.cfg
> xl console freebsd
>
> This is what happens when I launch the vm :
>
> # ./start-freebsd
>
> Parsing config from freebsd.cfg
> xc: error: panic: xg_dom_core.c:689: xc_dom_find_loader: no loader found:
> Invalid kernel
> libxl: error: libxl_dom.c:571:libxl__build_dom: xc_dom_parse_image failed
> libxl: error: libxl_create.c:1640:domcreate_rebuild_done: Domain 1:cannot
> (re-)build domain: -3
> libxl: error: libxl_domain.c:1183:libxl__destroy_domid: Domain
> 1:Non-existent domain
> libxl: error: libxl_domain.c:1137:domain_destroy_callback: Domain 1:Unable
> to destroy guest
> libxl: error: libxl_domain.c:1064:domain_destroy_cb: Domain 1:Destruction
> of domain failed
> freebsd is an invalid domain identifier (rc=-6)
>
>
> On Mon, Dec 18, 2023 at 12:39 PM Mario Marietto <marietto2008@gmail.com>
> wrote:
>
>> So,ok,I should have said "the second u-boot" ; since the first u-boot
>> binary is the "u-boot binary located in the RO memory" of the Chromebook".
>> Sorry for the confusion.
>>
>> On Mon, Dec 18, 2023 at 12:35 PM Mario Marietto <marietto2008@gmail.com>
>> wrote:
>>
>>> ---> There are no specific options in u-boot devoted to FreeBSD
>>>
>>> This is an important factor. So,what about if,instead of compiling a new
>>> version of u-boot on the partition 2,I will recompile the u-boot customized
>>> version created by the virtual open system in 2014,that should be installed
>>> on the first partition ? It could work if there are no differences between
>>> the u-boot that should boot Linux and the u-boot that should boot FreeBSD.
>>>
>>> Can you give a look at the u-boot source code created by virtual open
>>> systems ? You can find it on my google drive :
>>>
>>>
>>> https://drive.google.com/file/d/1eAaZMfd6CU0xiqQfH7sq5wGVzzO09BRm/view?usp=sharing
>>>
>>> I need to understand if I can recompile it without problem so that it
>>> can satisfy my needs (the ability of the file u-boot.bin to boot FreeBSD as
>>> domU under Xen,as explained by Stefano Stabellini,the xen developer that
>>> suggested to me what I could do to have FreeBSD virtualized under Xen on my
>>> Arm Chromebook) ; otherwise the risk is to find later problems that will
>>> make me troubles and that I will not able to fix.
>>>
>>> I gave a look at the virtual open system u-boot and I didn't see any arndale_defconfig
>>> inside. So,If I have understood correctly,I should put that file inside the
>>> root of the u-boot source code,let's say here :
>>>
>>> marietto:/home/marietto/Desktop/Files/u-boot_FreeBSD/u-boot-vos # ls
>>>
>>> .checkpatch.conf        README                  doc
>>>                     net
>>> .git                    api                     drivers
>>>                 onenand_ipl
>>> .gitignore              arch                    dts
>>>                     post
>>> COPYING                 board                   examples
>>> rules.mk
>>> CREDITS                 boards.cfg              fs
>>>                      scripts
>>> MAINTAINERS             common                  include
>>>                 snapshot.commit
>>> MAKEALL                 config.mk               lib
>>>                     spl
>>> Makefile                cros                    mkconfig
>>>                test
>>> PRESUBMIT.cfg           disk                    nand_spl
>>>                tools
>>>
>>> and I should do : make and make install ? and the file I need,u-boot.bin
>>> will be generated ?
>>>
>>> I didn't find any pre made configuration file inside :
>>>
>>> u-boot-vos # find . -type f -name "exynos*"
>>>
>>> ./include/exynos-fb.h
>>> ./include/configs/exynos5-common.h
>>> ./doc/device-tree-bindings/spi/exynos-spi.txt
>>> ./doc/device-tree-bindings/usb/exynos-usb.txt
>>> ./drivers/power/exynos-tmu.c
>>> ./drivers/power/exynos-cpufreq.c
>>> ./drivers/video/exynos-fb.c
>>> ./drivers/spi/exynos_spi.c
>>> ./board/samsung/dts/exynos5250-spring.dts
>>> ./board/samsung/dts/exynos5250-smdk5250.dts
>>> ./board/samsung/dts/exynos5250-snow.dts
>>> ./board/samsung/dts/exynos5250-daisy.dts
>>> ./arch/arm/include/asm/arch-exynos5/exynos-cpufreq.h
>>> ./arch/arm/include/asm/arch-exynos5/exynos-tmu.h
>>> ./arch/arm/dts/exynos5250.dtsi
>>> ./arch/arm/dts/exynos-periph-id.dtsi
>>> ./arch/arm/cpu/armv7/exynos5/exynos_cache.c
>>>
>>> u-boot-vos # find . -type f -name "arndale*"
>>>
>>> For sure I can't use a newer version of u-boot because otherwise the
>>> patches needed to bypass the bootloader protections of the Arm Chromebook
>>> (such as a lot of different patches needed to boot correctly Linux) will be
>>> broken ; anyway,since it works,I don't need to use an updated version of
>>> u-boot.
>>>
>>> ----> As per my experience, you have to respect these two options,
>>> compiling u-boot for FreeBSD:
>>> https://github.com/freebsd/freebsd-ports/blob/main/sysutils/u-boot-master/files/FreeBSD_Fragment
>>>
>>> It says that I should use these parameters :
>>>
>>> CONFIG_ARMV7_NONSEC=n
>>> CONFIG_EFI_GRUB_ARM32_WORKAROUND=y
>>>
>>> These are the parameters used to configure a Linux kernel. I don't
>>> understand what's the relation between the compilation of a linux kernel
>>> and u-boot. In the past I tried to recompile u-boot,but I didn't have the
>>> need to set up those parameters,so I don't know how to do it (but I know
>>> how to recompile a Linux kernel).
>>>
>>>
>>> ---> I'm not sure that I'm getting you right, as I don't understand what
>>> you mean under "the first u-boot".
>>>
>>>
>>> I'm talking about first u-boot because the whole procedure to boot Linux
>>> on the ARM Chromebook,that's explained here :
>>>
>>> http://www.virtualopensystems.com/en/solutions/guides/kvm-on-chromebook/
>>>
>>>
>>> at some point they say :
>>>
>>>
>>> To be able to run KVM on ARM platforms, the kernel has to be booted in
>>> hypervisor mode. Because of this relatively recent requirement (due to the
>>> introduction of the virtualization extensions), up until now all booting
>>> methods would boot the kernel in the standard Supervisor mode.
>>>
>>> For the ARM Chromebook the default boot procedure doesn't allow us to
>>> boot in hypervisor mode. Although the laptop's boot mechanism is based on
>>> the frequently used u-boot, the binary is located in RO memory.
>>> Fortunately, a chained u-boot mechanism can be used (i.e. starting another
>>> u-boot after the original). We can then enter hypervisor mode from our
>>> custom iteration of u-boot and subsequently load our kernel and userspace.
>>>
>>> So,the first u-boot is the u-boot provided by virtual open
>>> systems,that's able to chainload the "u-boot binary located in RO memory" ,
>>> that does not boot Chrome OS in hypervisor mode. We don't need it if we
>>> want to boot Linux with kvm or xen enabled.
>>>
>>> On Sun, Dec 17, 2023 at 1:28 AM Stanislav Silnicki <
>>> stanislav.silnicki@mailgate.us> wrote:
>>>
>>>> I'm not an expert in the topic, I only know, that ARM has divided
>>>> hardware into two worlds - Secure and Not-So, strictly limiting any
>>>> software, running in non-secure world with access to functions and
>>>> resources.
>>>> https://developer.arm.com/documentation/den0013/d/Security/TrustZone-hardware-architecture?lang=en
>>>>
>>>> I'm not sure, that I'm getting you right, as I don't understand what
>>>> you mean under "the first u-boot".
>>>>
>>>> As I understand, virtualization (HYP) is running in non-secure world (
>>>> https://developer.arm.com/documentation/ddi0406/c/System-Level-Architecture/The-System-Level-Programmers--Model/The-Virtualization-Extensions),
>>>> so my guess (only guess!!!), virtualization software has to prepare
>>>> (configure) HW platform in the way, that FreeBSD kernel will not lack any
>>>> resources, required to configure MPU, VA, etc.
>>>> So, if you lucky to boot virtualizer, which is aware of target OS, that
>>>> maybe you can boot the kernel. Although, I doubt, that you need to boot
>>>> 'second' u-boot to boot the kernel - there is simply ubldr, which you can
>>>> hook somehow from virtualizer....
>>>>
>>>> Stan
>>>>
>>>>
>>>>
>>>> Mario Marietto wrote:
>>>>
>>>>
>>>> ---> As I understand, it makes sure that u-boot keeps in secure mode
>>>> during boot and passes control to ubldr, which boots FreeBSD kernel, in
>>>> that mode.
>>>>
>>>> Can you elaborate your sentence more ? I know that the bootloader
>>>> secure mode is bypassed by the virtual open systems u-boot. Are you saying
>>>> that when the control passes to the second u-boot,it will happen in secure
>>>> mode,so that the bypass that happened loading the first u-boot,is annulled
>>>> ? If this is true,maybe can I boot FreeBSD using the virtual-open-system
>>>> custom u-boot ? Is this compatible with FreeBSD ? Where can I find the
>>>> u-boot.bin that the xen developer talked about ? thanks bro'.
>>>>
>>>>
>>>>
>>>> On Sun, Dec 17, 2023 at 12:35 AM Stanislav Silnicki <
>>>> stanislav.silnicki@mailgate.us> wrote:
>>>>
>>>>> Hi Mario,
>>>>>
>>>>> U-Boot  beast is hiding in this den:
>>>>> https://source.denx.de/u-boot/u-boot.git
>>>>> I took a brief look at your post and it seems to me, that option
>>>>> CONFIG_CMO_BY_VA_ONLY is irrelevant to your target armv7 32 bit
>>>>> platform:
>>>>> https://source.denx.de/u-boot/u-boot/-/blob/master/arch/arm/cpu/armv8/Kconfig?ref_type=heads#L3
>>>>>
>>>>> As for compiling the u-boot, it is a doable task, given that you
>>>>> understand what you are doing. There are no specific options in u-boot
>>>>> devoted to FreeBSD. It is a boot loader, whose mission to make basic
>>>>> hardware initialization, read you kernel file from some media into RAM and
>>>>> then pass it control.
>>>>>
>>>>> Basically, you can grab some defconfig, prepared for any other
>>>>> Exynos5250 based board  (say, this one:
>>>>> https://source.denx.de/u-boot/u-boot/-/blob/master/configs/arndale_defconfig?ref_type=heads)
>>>>> and adopt it somehow.
>>>>>
>>>>> As per my experience, you have to respect these two options, compiling
>>>>> u-boot for FreeBSD:
>>>>> https://github.com/freebsd/freebsd-ports/blob/main/sysutils/u-boot-master/files/FreeBSD_Fragment
>>>>>
>>>>> As I understand, it makes sure, that u-boot keeps in secure mode
>>>>> during boot and passes control to ubldr, which boots FreBSD kernel, in that
>>>>> mode. Otherwise, there a lot of surprises you may realize.
>>>>>
>>>>> Hope, this will help to progress you tasks
>>>>> Stan
>>>>>
>>>>> Mario Marietto wrote:
>>>>>
>>>>>
>>>>> Hello.
>>>>>
>>>>> I'm trying to boot FreeBSD for arm32 bit as DomU on my ARM Chromebook.
>>>>> Basically there are two ways to accomplish this task :
>>>>>
>>>>> 1) to write a patch that allows the FreeBSD kernel to boot as a zImage
>>>>> file. This could be accomplished applying this patch to a specific file
>>>>> that's on the source code of FreeBSD :
>>>>>
>>>>>
>>>>>
>>>>> https://xenbits.xen.org/gitweb/?p=p...8;hb=0782e25d98cc1391472717035f986c979edef0c9
>>>>> <https://xenbits.xen.org/gitweb/?p=people/julieng/freebsd.git;a=blob_plain;f=sys/arm/conf/XENVIRT;h=ff6433392e6fc2d5fa7c1ad1f7c40155003af9a8;hb=0782e25d98cc1391472717035f986c979edef0c9>
>>>>>
>>>>>
>>>>> This patch was written by Julien Grall a lot of time ago and now it
>>>>> does not work anymore. This is the reason :
>>>>>
>>>>>
>>>>> It appears FreeBSD-CURRENT removed the last step converting the kernel
>>>>> file to kernel.bin. The patch can be readily rebased, but without
>>>>> kernel.bin that doesn't do too much.
>>>>>
>>>>>
>>>>>
>>>>> So,without a rebase of that patch the first option is not applicable.
>>>>> And I'm not able to fix it.
>>>>>
>>>>> 2) booting FreeBSD using U-Boot,as explained to me by a xen developer :
>>>>>
>>>>>
>>>>> I was trying to explain why and how Julien's patch works so that you
>>>>> could be the one to re-do something similar or fix the patch on the FreeBSD
>>>>> kernel that you are working with. I am happy to help review and write
>>>>> patches but I don't work with the FreeBSD kernel so I wouldn't be able to
>>>>> help you quickly. However, I might have a suggestion. Do you know if
>>>>> FreeBSD can be booted by U-Boot ? Because U-Boot definitely boots as Xen on
>>>>> ARM guest firmware/bootloader. You should be able to build U-Boot and use
>>>>> the U-Boot binary as Xen guest kernel, then U-Boot could load FreeBSD from
>>>>> disk or network and start it. For instance as domU config file:
>>>>>
>>>>> kernel="/home/petalinux/u-boot.bin"
>>>>> disk = [ '/home/petalinux/test.img,raw,xvda' ]
>>>>>
>>>>> I know it is important to build u-boot with the following config to
>>>>> make it work on Xen.
>>>>>
>>>>> CONFIG_CMO_BY_VA_ONLY=y
>>>>>
>>>>>
>>>>>
>>>>> This option seems more doable to me according to my knowledge. But I
>>>>> need to understand how to do it.
>>>>>
>>>>> Well,let's say that on the ARM Chromebook I'm forced to use and
>>>>> install a customized version of u-boot,created by virtual open
>>>>> systems,because it is the only one that allows bypassing its bootloader
>>>>> protection. You can find more information here :
>>>>>
>>>>>
>>>>> http://www.virtualopensystems.com/en/solutions/guides/kvm-on-chromebook/?vos=tech
>>>>>
>>>>> This is the relevant section to read :
>>>>>
>>>>>
>>>>> Bootloader :
>>>>>
>>>>> If you wish to skip this chapter you can download a pre-compiled
>>>>> binary of the bootloader:
>>>>>
>>>>>
>>>>> $ wget
>>>>> http://www.virtualopensystems.com/downloads/guides/kvm_on_chromebook/nv_u-boot-snow.kpart
>>>>>
>>>>>
>>>>> To be able to run KVM on ARM platforms, the kernel has to be booted in
>>>>> hypervisor mode. Because of this relatively recent requirement (due to the
>>>>> introduction of the virtualization extensions), up until now all booting
>>>>> methods would boot the kernel in the standard Supervisor mode. For the ARM
>>>>> Chromebook the default boot procedure doesn't allow us to boot in
>>>>> hypervisor mode. Although the laptop's boot mechanism is based on the
>>>>> frequently used u-boot, the binary is located in RO memory. Fortunately, a
>>>>> chained u-boot mechanism can be used (i.e. starting another u-boot after
>>>>> the original). We can then enter hypervisor mode from our custom iteration
>>>>> of u-boot and subsequently load our kernel and userspace.
>>>>>
>>>>> Checkout the needed u-boot code :
>>>>>
>>>>>
>>>>> $ git clone git://github.com/virtualopensystems/u-boot.git$ cd
>>>>> u-boot$ ./scripts/build.sh
>>>>>
>>>>>
>>>>> If successful, a message about how to copy the bootloader on the USB
>>>>> flash disk or SD card will appear. We will use it later when preparing the
>>>>> boot medium to start our system. If you have followed the Setting up the
>>>>> boot medium chapter and you have a prepared boot device, then you can
>>>>> update u-boot by running :
>>>>>
>>>>>
>>>>> $ sudo dd if=nv_uboot-snow.kpart of=/dev/sdX1
>>>>>
>>>>>
>>>>>
>>>>> so,the needed u-boot that we must use should be installed on the first
>>>>> partition of the sd card.
>>>>>
>>>>> There is another relevant section to read :
>>>>>
>>>>>
>>>>> Setting up the boot medium
>>>>>
>>>>> Now it is time to copy all the relevant files that we created in the
>>>>> previous chapters,and use them to boot Chromebook with a different kernel
>>>>> and OS. In all these examples the device /dev/sdX is used. Take extra care
>>>>> to change the examples to the device that you have attached. Insert the
>>>>> boot medium on your workstation and carefully execute the following step.
>>>>> First we need to properly format the boot medium.
>>>>>
>>>>> In the uboot source directory :
>>>>>
>>>>>
>>>>> $ sudo ./scripts/sdcard.sh /dev/sdX
>>>>>
>>>>>
>>>>> This will erase all data and create 4 partitions in the medium, along
>>>>> with copying the u-boot binary to the first partition:
>>>>>
>>>>>
>>>>> Partition 1 = ChromeOS signed binary (V.O.S chained u-boot)
>>>>> Partition 2 = not used
>>>>> Partition 3 = EXT2 partition for u-boot files (uImage and
>>>>> exynos5250-snow.dtb)
>>>>> Partition 4 = EXT4 partition for userspace files
>>>>>
>>>>>
>>>>> With u-boot being copied, next is the kernel image and DTB file. From
>>>>> the kernel source execute :
>>>>>
>>>>>
>>>>> $ mkdir ../mnt/
>>>>> $ sudo mount /dev/sdX3 ../mnt/
>>>>> $ sudo cp arch/arm/boot/uImage ../mnt/
>>>>> $ sudo cp arch/arm/boot/dts/exynos5250-snow.dtb ../mnt/
>>>>> $ sudo umount /dev/sdX3
>>>>>
>>>>>
>>>>> Finally, we have to copy the Ubuntu userspace filesystem that we
>>>>> created earlier:
>>>>>
>>>>>
>>>>> $ sudo mount /dev/sdX4 mnt/$ sudo cp -a ./precise/* mnt/$ sudo umount
>>>>> /dev/sdX4
>>>>>
>>>>>
>>>>>
>>>>> Now,my idea is to chainload the already chain loaded u-boot created by
>>>>> V.O.S to the new u-boot that we need for booting FreeBSD and that can be
>>>>> installed in the partition n.2,as shown in this scheme,because it is not
>>>>> used :
>>>>>
>>>>>
>>>>> Partition 1 = ChromeOS signed binary (V.O.S chained u-boot)
>>>>> Partition 2 = not used (maybe we can install the u-boot for arm 32
>>>>> bit,compatible with FreeBSD on this partition)
>>>>> Partition 3 = EXT2 partition for u-boot files (uImage and
>>>>> exynos5250-snow.dtb)
>>>>> Partition 4 = EXT4 partition for userspace files
>>>>>
>>>>>
>>>>> Take in consideration that default boot string is hardcoded here,in
>>>>> the snow.h file of the custom u-boot created by VOS :
>>>>>
>>>>>
>>>>>
>>>>> https://github.com/virtualopensyste...18a39b6c177dff58a/include/configs/snow.h#L101
>>>>> <https://github.com/virtualopensystems/u-boot/blob/eecfeb578e296ef3b739ac918a39b6c177dff58a/include/configs/snow.h#L101>
>>>>>
>>>>>
>>>>> and it needs to be recompiled because it should point to the partition
>>>>> n.2,where I will install the u-boot files as explained here :
>>>>>
>>>>>
>>>>> https://wiki.freebsd.org/arm/Chromebook
>>>>>
>>>>>
>>>>> I have some questions to ask before I start working on this.
>>>>>
>>>>> 1) The xen developer said :
>>>>>
>>>>>
>>>>> You should be able to build U-Boot and use the U-Boot binary as Xen
>>>>> guest kernel...
>>>>>
>>>>>
>>>>>
>>>>> where is the u-boot binary,according to this document ?
>>>>>
>>>>> https://wiki.freebsd.org/arm/Chromebook
>>>>>
>>>>> I don't see it.
>>>>>
>>>>>
>>>>> 2) where is the source code of the file that I can get here :
>>>>>
>>>>>
>>>>> http://commondatastorage.googleapis.com/chromeos-localmirror/distfiles/nv_uboot-snow-simplefb.kpart.bz2
>>>>>
>>>>> I need the source code if I want to recompile u-boot so that it can
>>>>> point to the partition 4.
>>>>>
>>>>> Maybe it can be found on this link :
>>>>>
>>>>> http://linux-exynos.org/dist/chromebook/nv_uboot/
>>>>>
>>>>> but it can't be opened....
>>>>>
>>>>>
>>>>> 3) in this specific scenario the source code of u-boot should run on
>>>>> arm 32 bit,not on arm 64,because I have the Samsung Chromebook "SNOW" model
>>>>> XE303C12,that's powered by a Samsung Exynos 5250 (ARMv7 32 bit Cortex A15)
>>>>> Soc.
>>>>>
>>>>>
>>>>> 4) I'm not sure if I can chainload the customized u-boot created by
>>>>> V.O.S that should be installed on the first partition with the u-boot
>>>>> tailored for booting FreeBSD that should be installed on the partition 2....
>>>>>
>>>>>
>>>>> 5) the xen developer said that u-boot should be compiled enabling this
>>>>> option :
>>>>>
>>>>>
>>>>> Code:
>>>>>
>>>>> CONFIG_CMO_BY_VA_ONLY=y
>>>>>
>>>>>
>>>>>
>>>>> Well,can you provide some good source that can help me to understand
>>>>> how I can recompile u-boot for FreeBSD ? thanks.
>>>>>
>>>>> --
>>>>> Mario.
>>>>>
>>>>>
>>>>
>>>> --
>>>> Mario.
>>>>
>>>>
>>>
>>> --
>>> Mario.
>>>
>>
>>
>> --
>> Mario.
>>
>
>
> --
> Mario.
>


-- 
Mario.