Re: [RFC PATCH] kexec, x86/boot: map systab region in identity mapping before accessing it

[Baoquan He <bhe@redhat.com>]

On 04/19/19 at 01:36pm, Borislav Petkov wrote:
> On Fri, Apr 19, 2019 at 01:28:01PM +0200, Borislav Petkov wrote:
> > 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".
> 
> And by that I mean similar to the XLF_EFI_KEXEC mechanism. The first
> kernel or kexec(1) should prepare the info needed by the kexec'ed
> kernel.

We have set the loader type to '0x0D << 4' for kexec specifically, in both
kexec_load and kexec_file_load. We can check this to identify if it's
kexec-ed kernel or not.

Update patch with it?

static void *bzImage64_load(struct kimage *image, char *kernel,
                            unsigned long kernel_len, char *initrd,
                            unsigned long initrd_len, char *cmdline,
                            unsigned long cmdline_len)
{

	...
	/* bootloader info. Do we need a separate ID for kexec kernel loader? */
        params->hdr.type_of_loader = 0x0D << 4;
	...

}