[arch-releng] [PATCH] archiso_loop_mnt - cleaner boot from loopmounted iso file
Gerardo Exequiel Pozzi
vmlinuz386 at gmail.com
Sat Jul 18 17:29:25 UTC 2015
On 07/18/2015 09:18 AM, Adam Purkrt wrote:
> On 07/13/2015 04:19 AM, Gerardo Exequiel Pozzi wrote:
>> On 07/12/2015 09:19 AM, Adam Purkrt wrote:
>>> On 07/12/2015 02:29 AM, Gerardo Exequiel Pozzi wrote:
>>>> On 07/11/2015 04:00 PM, Adam Purkrt wrote:
>>>>> I would like to suggest the patch below, to archiso_loop_mnt hook.
>>>>>
>>>>> Currently, when booting loopmounted iso file, it is necessary to
>>>>> specify not only img_dev and img_loop (which should be sufficient),
>>>>> but also archisolabel or archisodevice. With the patch, archisodevice
>>>>> is directly populated with the correct loop device, and it is not
>>>>> necessary to specify the label when booting from loopmounted iso,
>>>>> which makes for leaner and cleaner grub.cfg.
>>>>>
>>>>> The kernel command line in grub.cfg currently needed:
>>>>>
>>>>> linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=ARCH_201507
>>>>> img_dev=$imgdevpath img_loop=$isofile earlymodules=loop
>>>>>
>>>>> after the patch:
>>>>>
>>>>> linux (loop)/arch/boot/x86_64/vmlinuz img_dev=$imgdevpath
>>>>> img_loop=$isofile earlymodules=loop
>>>>>
>>>> You are right!
>>>>
>>>> Please also update the README.altbootmethods ;)
>>>>
>>>> PS: "earlymodules=loop": Is like a copy&paste hurricane from old age.
>>>> It was a temporal workaround (2011.08.19), but spread across all places.
>>>>
>>>> Thanks.
>>>>
>>>
>>> It's good that "earlymodules=loop" is not necessary, thanks for pointing it out.
>>>
>>> Updated the README.altbootmethods, using uuid over label. Overall the patch is:
>>>
>>> diff --git a/archiso/initcpio/hooks/archiso_loop_mnt b/archiso/initcpio/hooks/archiso_loop_mnt
>>> index 46338e5..f95a47d 100644
>>> --- a/archiso/initcpio/hooks/archiso_loop_mnt
>>> +++ b/archiso/initcpio/hooks/archiso_loop_mnt
>>> @@ -18,7 +18,9 @@ archiso_loop_mount_handler () {
>>> echo $(readlink -f ${img_dev}) >> /run/archiso/used_block_devices
>>> fi
>>>
>>> - if ! _dev_loop=$(losetup --find --show --read-only "/run/archiso/img_dev/${img_loop}"); then
>>> + if _dev_loop=$(losetup --find --show --read-only "/run/archiso/img_dev/${img_loop}"); then
>>> + archisodevice="${_dev_loop}"
>>> + else
>>> echo "ERROR: Setting loopback device for file '/run/archiso/img_dev/${img_loop}'"
>>> launch_interactive_shell
>>> fi
>>> diff --git a/docs/README.altbootmethods b/docs/README.altbootmethods
>>> index 3c07e03..cbfada4 100644
>>> --- a/docs/README.altbootmethods
>>> +++ b/docs/README.altbootmethods
>>> @@ -25,20 +25,23 @@ Where:
>>>
>>> Note: Described method is for using with GRUB2.
>>> GRUB2 is installed on target media and archlinux-<YYYY>.<MM>.<DD>-dual.iso
>>> - is at path <TARGET-PATH> on disk <D> and partition <P>,
>>> - where filesystem is labeled as <TARGET-FS-LABEL>.
>>> + is at path <TARGET-PATH> on disk <D> and partition <P>.
>>>
>>> menuentry "Arch Linux (x86_64)" {
>>> + set isopartition=hd<D>,<P>
>>> set isofile="/<TARGET-PATH>/archlinux-<YYYY>.<MM>.<DD>-dual.iso"
>>> - loopback loop (hd<D>,<P>)$isofile
>>> - linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=<FS-LABEL> img_label=<TARGET-FS-LABEL> img_loop=$isofile
>>> + loopback loop ($isopartition)$isofile
>>> + probe -u $isopartition --set=isouuid
>>> + linux (loop)/arch/boot/x86_64/vmlinuz img_dev=/dev/disk/by-uuid/$isouuid img_loop=$isofile
>>> initrd (loop)/arch/boot/x86_64/archiso.img
>>> }
>>>
>>> menuentry "Arch Linux (i686)" {
>>> + set isopartition=hd<D>,<P>
>>> set isofile="/<TARGET-PATH>/archlinux-<YYYY>.<MM>.<DD>-dual.iso"
>>> - loopback loop (hd<D>,<P>)$isofile
>>> - linux (loop)/arch/boot/i686/vmlinuz archisolabel=<FS-LABEL> img_label=<TARGET-FS-LABEL> img_loop=$isofile
>>> + loopback loop ($isopartition)$isofile
>>> + probe -u $isopartition --set=isouuid
>>> + linux (loop)/arch/boot/i686/vmlinuz img_dev=/dev/disk/by-uuid/$isouuid img_loop=$isofile
>>> initrd (loop)/arch/boot/i686/archiso.img
>>> }
>>>
>>>
>>>
>>>
>>>
>>>
>>> One more thing - I would vote for deprecating "img_label" parameter and (sooner or later) removing it, i.e.
>>>
>>> /archiso/initcpio/hooks/archiso_loop_mnt
>>> - [[ -n "${img_label}" ]] && img_dev="/dev/disk/by-label/${img_label}"
>>>
>>> /docs/README.bootparams
>>> -* img_label= Set the filesystem label where archiso-image.iso.
>>> - Default: (unset)
>>> * img_dev= Device where archiso-image.iso reside.
>>> - Default: (unset) or "/dev/disk/by-label/${img_label}"
>>> + Default: (unset)
>>>
>>> since: 1) it is more reliable to refer to a partition by uuid
>>> 2) there is no "img_uuid" - and I don't think there should be, "img_dev=/dev/disk/by-uuid/[uuid]" is perfectly fine
>>> 3) it would be still possible to address by label using "img_dev=/dev/disk/by-label/[label]"
>>>
>>> Not sure how much upheaval the abolition of img_label would cause, though.
>>>
>>
>> Please do one logic change at time.
>> Wheel, I never used loopback method other than just for test it per user
>> request when it was implemented.
>> Why remove img_label= it does look good for keep thing easy to
>> reference, sure archisolabel= can also be removed...
>>
>>
>>
>
> Perhaps the following change is more acceptable. Admittedly, in many situations,
> using label can be quite practical.
Sure.
>
> Booting from iso, in general, comes in handy; you don't need to overwrite a whole flash.
There is no need to do such thing. The ISO is made in a way to just copy
one directory, all is self contained in "arch". (minus bootloader)
> On efi systems it is sufficient to simply copy /EFI/ and /boot/ directory from some
> distro with grub, then copy the iso file to /boot/iso/, tailor /boot/grub/grub.cfg
> and you have an (efi) bootable flash, without a need to overwrite the flashdrive.
>
>
> diff --git a/archiso/initcpio/hooks/archiso_loop_mnt b/archiso/initcpio/hooks/archiso_loop_mnt
> index 46338e5..f95a47d 100644
> --- a/archiso/initcpio/hooks/archiso_loop_mnt
> +++ b/archiso/initcpio/hooks/archiso_loop_mnt
> @@ -18,7 +18,9 @@ archiso_loop_mount_handler () {
> echo $(readlink -f ${img_dev}) >> /run/archiso/used_block_devices
> fi
>
> - if ! _dev_loop=$(losetup --find --show --read-only "/run/archiso/img_dev/${img_loop}"); then
> + if _dev_loop=$(losetup --find --show --read-only "/run/archiso/img_dev/${img_loop}"); then
> + archisodevice="${_dev_loop}"
> + else
> echo "ERROR: Setting loopback device for file '/run/archiso/img_dev/${img_loop}'"
> launch_interactive_shell
> fi
OK
> diff --git a/docs/README.altbootmethods b/docs/README.altbootmethods
> index 3c07e03..9df20ef 100644
> --- a/docs/README.altbootmethods
> +++ b/docs/README.altbootmethods
> @@ -31,14 +31,14 @@ Note: Described method is for using with GRUB2.
> menuentry "Arch Linux (x86_64)" {
> set isofile="/<TARGET-PATH>/archlinux-<YYYY>.<MM>.<DD>-dual.iso"
> loopback loop (hd<D>,<P>)$isofile
> - linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=<FS-LABEL> img_label=<TARGET-FS-LABEL> img_loop=$isofile
> + linux (loop)/arch/boot/x86_64/vmlinuz img_label=<TARGET-FS-LABEL> img_loop=$isofile
> initrd (loop)/arch/boot/x86_64/archiso.img
> }
>
> menuentry "Arch Linux (i686)" {
> set isofile="/<TARGET-PATH>/archlinux-<YYYY>.<MM>.<DD>-dual.iso"
> loopback loop (hd<D>,<P>)$isofile
> - linux (loop)/arch/boot/i686/vmlinuz archisolabel=<FS-LABEL> img_label=<TARGET-FS-LABEL> img_loop=$isofile
> + linux (loop)/arch/boot/i686/vmlinuz img_label=<TARGET-FS-LABEL> img_loop=$isofile
> initrd (loop)/arch/boot/i686/archiso.img
> }
>
OK
> diff --git a/docs/README.bootparams b/docs/README.bootparams
> index 356375d..48a1c3a 100644
> --- a/docs/README.bootparams
> +++ b/docs/README.bootparams
> @@ -20,6 +20,9 @@ INDEX
> * archisolabel= Set the filesystem label where archiso files reside.
> Default: (unset)
> * archisodevice= Set the device node where archiso medium is located.
> + Upon successful mount of the iso image specified by
> + img_dev and img_loop, it is automatically set to the
> + appropriate loop device.
> Default: "/dev/disk/by-label/${archisolabel}"
> * archisobasedir= Set the base directory where all files reside.
> Default: "arch"
>
Discard. Is "like" when boot via PXE.
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