[systemd-devel] [PATCH] shutdown: add kexec loading, avoid calling `kexec` binary unnessecarily

[Shawn Landden]

On Wed, Mar 11, 2015 at 6:24 PM, Kay Sievers <kay at vrfy.org> wrote:

> On Thu, Mar 12, 2015 at 2:07 AM, Shawn Landden <shawn at churchofgit.com>
> wrote:
> > On Wed, Mar 11, 2015 at 5:51 PM, Kay Sievers <kay at vrfy.org> wrote:
> >>
> >> On Thu, Mar 12, 2015 at 1:22 AM, Shawn Landden <shawn at churchofgit.com>
> >> wrote:
> >> > Still use helper when Xen Dom0, to avoid duplicating some hairy code.
> >> >
> >> > I think the rbtree version was far more understandable as
> >> > greedy_realloc0()
> >> > is very messy to do correctly.
> >> >
> >> > Take fopenat() from lsof.
> >> > Add opendirat()
> >>
> >> We have that in util.c :: xopendirat()
> >>
> >> > Future: generate BootLoaderSpec files for other kernel install
> locations
> >>
> >> This approach duplicates, the potentially complex, boot manager kernel
> >> selection logic.
> >>
> >> The recent systemd-boot boot loader and efi stub loader which carries
> >> the kernel, the cmdline, the initrd in one single EFI binary will also
> >> not use any boot loader snippets, it will be discovered by the loader
> >> itself, which parses the PE/COFF files and looks for specific content.
> >>
> >> The snippets are meant to unify the boot loader *configuration*, but
> >> they do not mean that every bootable kernel will or should have one.
> >> There might be many ways for kernels to be found by the boot loader,
> >> the snippets are just one source for that.
> >>
> >> I'm not sure what exact problem this patch tries to solve,
> >
> > rebooting with kexec is faster than a full reboot. Currently we do not
> > support kexec very well. Lennart asked for something like this, but
> perhaps
> > we no longer want to support kexec loading?
>
> I kind of miss a description what this change is supposed to support
> in the end. It can't be described with "replacing a call to a binary".
>
> Automatic searching and deciding what kernel to boot, and how to
> search for these kernels, and how all that should continue to work
> reliably in the longer run, while the boot loaders underneath improve
> and change; that is something we should define before and have a clear
> idea, before we copy only parts of that logic from the current tools.
>
> I thought you wrote a specification?
freedesktop.org/wiki/Specifications/BootLoaderSpec/

Anyways, you should at least merge this patch:

1423865887-1507-1-git-send-email-shawn at churchofgit.com

 (
https://www.mail-archive.com/systemd-devel@lists.freedesktop.org/msg28005.html
)

> Thanks,
> Kay
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>



-- 
Shawn Landden
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