[lkml]   [2019]   [Apr]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC PATCH] kexec, x86/boot: map systab region in identity mapping before accessing it
On Fri, Apr 19, 2019 at 06:50:14PM +0800, Baoquan He wrote:
> Talked with Kairui privately just now. Seems Junichi's patch need add
> this systab mapping. Since the systab region is not mapped on some
> machines. Those machine don't have this issue because they got systab
> region luckily coverred by 1 GB page mapping in 1st kernel before
> kexec jumping.

You don't have to repeat all I that - I know what the problem is. Read
what I said again: it is too late for 5.1 to do any involved surgery.

> > 2. Then, the fact whether the kernel has been kexec'ed and which
> > addresses it should use early, should all be passed through boot_params
> > which is either setup by kexec(1) or by the first kernel itself, in the
> > kexec_file_load() case.
> Seems no better way to check if it's kexec-ed kernel, except of the
> setup data checking of kexec-ed kernel.

Why does that "seem" so?

Read again what I said: "should all be passed through boot_params".
Which means, boot_params should be extended with a field of a flag to
say: "this is a kexec'ed kernel".

If it "seems" then it should be made to not "seem" but to work properly.

> Yeah, adding the systab mapping looks good. Kairui put it in
> decompressing stage just because he wants to cover the case in which the
> old kernel kexec jumping to 2nd kernel. Now it seems not very
> reasonable, we also have the new kernel kexec jumping to old 2nd kernel.

I don't think we can guarantee kexec between old<->new kernel to always
work. Otherwise, we can forget all development and improvements of new


Good mailing practices for 400: avoid top-posting and trim the reply.

 \ /
  Last update: 2019-04-19 20:40    [W:0.116 / U:5.484 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site