Re: Need help with Booting to LFS

On 9/13/25 12:42 PM, Richard Henschel ([email protected] via lfs-support 
Mailing List) wrote:
> On 9/13/25 03:32, Xi Ruoyao ([email protected] via lfs-support Mailing List) wrote:
> 
>> On Sat, 2025-09-13 at 02:54 -0500, Bruce Dubbs wrote:
>>> This should have been sent to LFS-support.
>>>
>>> On 9/13/25 1:31 AM, Vansh Mittal wrote:
>>>> Hello,
>>>>
>>>> I recently completed building *LFS 12.3 (sysv)* by following the book instructions,
>>>> but I am stuck at the final step: booting into the LFS system.
>>>>
>>>> On boot, I get the following error:
>>>>
>>>>> /dev/root: can't openblockdev |
>>>> My setup:
>>>>
>>>>    *
>>>>
>>>>      Booting via *UEFI*
>>>>
>>>>    *
>>>>
>>>>      Using an *NVMe SSD*
>>>>
>>>>    * Host*- 22.04 ubuntu*
>>>>
>>>> I have already checked the FAQ and tried the suggested fixes, but the issue persists.
>>>>
>>>> I tired getting help from LinuxQuestions but nothing fixed the issue. I think the
>>>> issue is in kernel config but i cant figure it our
>>>>
>>>> For reference, I have uploaded my *GRUB config, fstab, and kernel .config* here:
>>>> https://drive.google.com/drive/folders/1jW1_ulSu0qupzM5N4Qv1p0Yxqi67hjof<https:// 
>>>> drive.google.com/drive/folders/1jW1_ulSu0qupzM5N4Qv1p0Yxqi67hjof>
>>>>
>>>> Could you please take a look and suggest what I might be missing or misconfigured?
>> See
>> https://lists.linuxfromscratch.org/sympa/arc/blfs-support/2025-09/msg00017.html
>> for some hints.
> 
>   The LFS grub.cfg has:
> 
> cat > /boot/grub/grub.cfg << "EOF"
> |# Begin /boot/grub/grub.cfg set default=0 set timeout=5 insmod part_gpt insmod ext2 
> set root=(hd0,2) set gfxpayload=1024x768x32 menuentry "GNU/Linux, Linux 6.16.1-lfs- 
> r12.4-16" { linux /boot/vmlinuz-6.16.1-lfs-r12.4-16 root=/dev/sda2 ro }|
> EOF
> 
> Note "insmod ext2" in it?
> 
> You may need:
> 
> CONFIG_EXT4_USE_FOR_EXT2=y

It is not needed,  CONFIG_EXT4_FS=y handles ext2 and ext3 also.

I recommend using fdisk or gdisk from the host system to set a partition name.
Then use PARTLABEL like:

linux /vmlinuz-6.16.1 \
       root=PARTLABEL=lfs124 ro \
       raid=noautodetect \
       consoleblank=120

That is useful when we are not sure what /dev/<somedisk> will be named by the kernel.

Most commercial distros use something like
   root=UUID=ceed5ca6-d5cf-4ea8-af87-c7a65716ca52
but that requires an ininrd because the UUID refers to a filesystem UUID.

It is possible to use a PARTUUID without a initrd but that is different from the 
filesystem UUID. It is generally found at /dev/disk/by-partuuid

   -- Bruce


> 
> Note that I have this, and it works:
> 
> #
> # File systems
> #
> CONFIG_DCACHE_WORD_ACCESS=y
> CONFIG_VALIDATE_FS_PARSER=y
> CONFIG_FS_IOMAP=y
> CONFIG_FS_STACK=y
> CONFIG_BUFFER_HEAD=y
> CONFIG_LEGACY_DIRECT_IO=y
> # CONFIG_EXT2_FS is not set
> # CONFIG_EXT3_FS is not set
> CONFIG_EXT4_FS=y
> CONFIG_EXT4_USE_FOR_EXT2=y
> CONFIG_EXT4_FS_POSIX_ACL=y
> CONFIG_EXT4_FS_SECURITY=y
> # CONFIG_EXT4_DEBUG is not set
> CONFIG_JBD2=y
> # CONFIG_JBD2_DEBUG is not set
> CONFIG_FS_MBCACHE=y
> CONFIG_JFS_FS=m
> CONFIG_JFS_POSIX_ACL=y
> 
> I also have the following because I have a removable NVME on that interface on one 
> machine:
> 
> CONFIG_SATA_AHCI=y
> 
>

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