Re: [Xen-devel] [PATCH] build: save generated config in /boot

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jan 06, 2016 at 03:38:36AM -0700, Jan Beulich wrote:
> >>> On 06.01.16 at 11:31, <ian.campbell@xxxxxxxxxx> wrote:
> > On Wed, 2016-01-06 at 02:22 -0700, Jan Beulich wrote:
> >> > > > On 05.01.16 at 17:53, <cardoe@xxxxxxxxxx> wrote:
> >> > On 12/22/15 10:09 AM, Jan Beulich wrote:
> >> > > > > > On 22.12.15 at 17:02, <cardoe@xxxxxxxxxx> wrote:
> >> > > > How does it not make sense in this case? That's what Andrew and I
> >> > > > are
> >> > > > asking you to explain.
> >> > > 
> >> > > But I already explained it: The file isn't needed for booting.
> >> > 
> >> > One use of it in /boot would be to check the file in 20_linux_xen like
> >> > we check the kernel config for different options to add different
> >> > parameters.
> >> 
> >> Which, if you search for it, is a very controversial thing: I agree
> >> with the side demanding for grub to not inspect the kernel's
> >> .config.
> > 
> > What is the preferred mechanism for determining from the contents of /boot
> > whether an XSM entry should be produced or not?
> 
> I don't think this can be inferred - iirc even an XSM-enabled build
> can be booted without unless in some kind of strict mode? IOW
> this needs to be configured on the host, not guessed by
> inspecting .config. (And as a side note, inspecting .config doesn't

It's better to lower the hurdle for XSM adoption by instructing grub to
do sensible default than requiring users to produce entries by hand,
isn't it?

> truly require .config to be on the boot partition, unless such
> inspection would happen at boot time, which I don't think is the
> case.)
> 

Yes and no.

It's true that it can be placed anywhere on the file system as long as
grub (or any other tools that need to inspect it) can find it.

But how would you propose grub to deal with this? The location needs to
be "fixed" from then on and present forever. Either we need to persuade
every distro to accept our new less-well-known location to always place
.config there or we make them patch grub as they package Xen. This is
just unnecessary work.  Anywhere other than /boot is inferior IMHO.

Wei.

> Jan
> 
> 
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