[arch-releng] [DRAFT][RFC][PATCH][archiso] Add UEFI boot support via Linux >= 3.3 EFI boot stub.

[Keshav P R]

On Tue, Mar 27, 2012 at 07:04, Gerardo Exequiel Pozzi
<vmlinuz386 at yahoo.com.ar> wrote:
> On 03/26/2012 11:16 AM, Keshav P R wrote:
>>
>> On Tue, Mar 20, 2012 at 23:15, Gerardo Exequiel Pozzi
>> <vmlinuz386 at yahoo.com.ar>  wrote:
>>>>
>>>> This is going to increase the iso size like hell. Having the kernel
>>>> and initrd files within a FAT image inside the iso is not a good idea.
>>>> A 32 MB fat image, come on. I know this is required for CD booting,
>>>> but this is not a good idea with efistub efilinux or elilo etc. For
>>>> USB booting you can just have the files in the iso itself, wherein the
>>>> user simply extract the iso in a FAT32 USB and boots from it. I say
>>>> drop support for iso booting via this fat fs image and support uefi
>>>> boot only in case of USBs.
>>>>
>>>> Regards.
>>>>
>>>> Keshav
>>>>
>>> OK, so just ignore this draft patch. UEFI boot support can be made
>>> manually by the user, just doing a copy of vmlinuz to the right place and
>>> optionally installing a boot manager.
>>>
>>> A documentation on the wiki is sufficient.
>>
>> You might be interested in rEFInd-x86_64
>> https://aur.archlinux.org/packages.php?ID=57632 which provides a nice
>> menu for EFISTUB kernels.
>>
>> Related info :
>> http://www.rodsbooks.com/refind/linux.html
>> http://www.rodsbooks.com/efi-bootloaders/efistub.html
>>
>> [QUOTE from http://www.rodsbooks.com/refind/linux.html]
>> rEFInd looks for a file called linux.conf in the same directory as the
>> kernel file. This file is a practical requirement for booting from an
>> auto-detected kernel. It consists of a series of lines, each of which
>> consists of a label followed by a series of kernel options. The first
>> line sets default options, and subsequent lines set options that are
>> accessible from the main menu tag's submenu screen.
>>
>> The intent of this system is that distribution maintainers can place
>> their kernels, initial RAM disks, and a linux.conf file in their own
>> subdirectory on the ESP. rEFInd will detect their kernels and create
>> one main menu entry for each kernel. Each entry will implement as many
>> options as there are lines in the linux.conf file. In this way, two or
>> more distributions can each maintain their boot loader entries,
>> without being too concerned for who maintains rEFInd as a whole.
>> [/QUOTE]
>>
>> The filename has been changed to refind_linux.conf in the upstream git
>> repo so that it does not conflict with the proposed efistub config
>> file by kernel devs
>>
>> (http://sourceforge.net/p/refind/code/ci/c09200e2220b05bbade961bdc35f7da90d318abf/).
>>
>> This should be pretty straightforward to implement in Archiso. For
>> non-EFISTUB kernels like LTS ones, you can use efilinux-x86_64
>> https://aur.archlinux.org/packages.php?ID=57972 (Usage instructions -
>> http://thread.gmane.org/gmane.linux.kernel/1172645 and
>> http://article.gmane.org/gmane.linux.kernel/1175060). This might be a
>> good alternative for grub2 uefi boot, although booting i686 kernels in
>> x86_64 UEFI will not be supported by EFISTUB (which can be done using
>> grub2). Support for mixed arch booting seems to have been merged for
>> 3.4-rc1 .
>>
>> Regards.
>>
>> Keshav
>>
> Thanks for the work.
>
> But this only added the advantage of passing command line options to the
> kernel. We still need a "FAT image" with bootx64.efi (rEFInd) + vmlinuz.efi
> + archiso.img (initramfs) + refind*.conf (for El Torito) that was the main
> dissapointed issue. Otherwise rEFInd can not find what file to load.
>

No. In this case just rEFInd (and the required icons -  not all of
them) needs to be in the FAT image. The kernels and initramfs can be
in (ISO)/efi/(SUBDIR)/ along with (ISO)/efi/(SUBDIR)/refind_linux.conf
containing the kernel parameters. If the (SUBDIR) is "arch" , ie.
(ISO)/efi/arch/ , then refind will even display Archlinux icon making
it easy for the user to differentiate the iso kernels from other
kernels.

All the answers are at http://www.rodsbooks.com/refind/ .

Regards.

Keshav