Hello Stephen.
On 11-08-14 20:04, Stephen Warren wrote:
On 08/11/2014 11:51 AM, Jeroen Hofstee wrote:
Hello Stephan
On 11-08-14 18:53, Stephen Warren wrote:
On 08/10/2014 10:53 AM, Jeroen Hofstee wrote:
Hello Stephan,
On 10-08-14 05:11, Stephen Warren wrote:
The entire point of this series is to prevent distros from having to
install bootloader-specific boot configuration files.
>
I fail to see why this is something to pursue. Since the distro knows
the boot path, why should u-boot be polling all possible options?
This patch series allows U-Boot to find the OS and boot it. U-Boot is
searching for some kind of boot configuration file.
This part of the process is the same as the BIOS searching all known
possible boot devices for a partition marked bootable, and with a
valid MBR. Or, it's the same as UEFI searching all possible boot
devices for whatever config file or boot binary is mandated by UEFI.
Not in my mind, I am not against scanning the possible
boot devices, on the contrary, I am trying to add booting
the userland from usb instead of mmc for the rpi_b.
The following will tell U-Boot to only search USB for extlinux.conf.
setenv boot_targets usb
(you can put this into /uEnv.txt on the SD card if you want to avoid
editing U-Boot source code to make this change; there's no persistent
environment storage on the Pi, at least at the moment)
I am going to give up soon commenting on this. It is
applied anyway. My point is that I am making an image
without an extlinux.conf, I know that, I could tell it in a
boot.scr but yet this scripts now insist on searching for
extlinux.conf. Resulting in that I am tempted not to use
the script at all. The rpi_b is a bit different, but if u-boot
was in NAND e.g. you likely endup with a u-boot not polling
for extlinux.conf at all, since the downstream board vendor
also thought it is annoying startup delay / noise. So placing
it in uEnv is in general too late, since it already polled
several boot devices for extlinux.
> The
part I dislike is where it starts searching for specific files.
The equivalent would be your BIOS actively searching for GRUB,
LILO, Windows Boot manager etc. etc. and as a fallback
try the MBR.
...
Once U-Boot locates extlinux.conf or boot.scr, that file encodes what
files (kernel, DTB, initrd)
This is the part I get for free now with it, I don't really like it,
since if we take this road it ends up looking for e.g. grub.conf,
ubldr.conf, vxworks.conf etc etc.
No, Linux distros need to be able to install a single bootloader
configuration file to tell the bootloader how to boot.
Don't understand this, I though extlinux is yet another
chainloaded bootloader? I doubt there is "the bootloader".
I don't understand why it needs a single bootloader. It gets
in handy if the last bootloader is known, but I don't even see
why that is required.
I definitely don't want to add support for a ton of other bootloader
configuration file formats. There needs to be a single standard that
distros know they can rely on.
Well you added the first auto polled chainloaded
bootloader, this simply paves the way for adding more.
Also in this case the downstream provides information back,
albeit tiny, it does indicate if it is bootable and a label to explain
what is bootable.
I don't understand what that means.
As I tried to explain before, if you just add a boot.scr indicating this
is a extlinux image and how such a image should be booted, u-boot
can pick this up, instead of doing this poll for everything approach.
Regards,
Jeroen
_______________________________________________
U-Boot mailing list
[email protected]
http://lists.denx.de/mailman/listinfo/u-boot
