[arch-releng] [PATCH] archiso_loop_mnt - cleaner boot from loopmounted iso file
Gerardo Exequiel Pozzi
vmlinuz386 at gmail.com
Sun Jul 19 18:44:15 UTC 2015
On 07/19/2015 12:17 PM, Adam Purkrt wrote:
> On 07/18/2015 07:29 PM, Gerardo Exequiel Pozzi wrote:
>> 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.
>>
>>
>
> Good; can't wait to see the "OK" parts merged.
>
> AP
>
Send as clean-new-git-patch-email ;)
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