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Re: [PATCH v4 09/11] xen: add capability to load initrd outside of initi
From: |
Daniel Kiper |
Subject: |
Re: [PATCH v4 09/11] xen: add capability to load initrd outside of initial mapping |
Date: |
Mon, 22 Feb 2016 13:24:11 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Feb 22, 2016 at 10:18:38AM +0100, Juergen Gross wrote:
> On 22/02/16 09:42, Daniel Kiper wrote:
> > On Mon, Feb 22, 2016 at 07:03:17AM +0100, Juergen Gross wrote:
> >> Modern pvops linux kernels support an initrd not covered by the initial
> >> mapping. This capability is flagged by an elf-note.
> >>
> >> In case the elf-note is set by the kernel don't place the initrd into
> >> the initial mapping. This will allow to load larger initrds and/or
> >> support domains with larger memory, as the initial mapping is limited
> >> to 2GB and it is containing the p2m list.
> >>
> >> Signed-off-by: Juergen Gross <address@hidden>
> >> Reviewed-by: Daniel Kiper <address@hidden>
> >> ---
> >> V4: rename grub_xen_alloc_end() to grub_xen_alloc_final()
> >> ---
> >> grub-core/loader/i386/xen.c | 61
> >> ++++++++++++++++++++++++++++++--------
> >> grub-core/loader/i386/xen_fileXX.c | 3 ++
> >> include/grub/xen_file.h | 1 +
> >> 3 files changed, 52 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
> >> index 2e12763..22a94ae 100644
> >> --- a/grub-core/loader/i386/xen.c
> >> +++ b/grub-core/loader/i386/xen.c
> >> @@ -58,6 +58,7 @@ struct xen_loader_state {
> >> grub_uint64_t modules_target_start;
> >> grub_size_t n_modules;
> >> int loaded;
> >> + int alloc_end_called;
> >
> > alloc_end_called -> alloc_final_called
> >
> >> };
> >>
> >> static struct xen_loader_state xen_state;
> >> @@ -320,6 +321,28 @@ grub_xen_pt_alloc (void)
> >> }
> >>
> >> static grub_err_t
> >> +grub_xen_alloc_final (void)
> >> +{
> >> + grub_err_t err;
> >> +
> >> + if (xen_state.alloc_end_called)
> >> + return GRUB_ERR_NONE;
> >> + xen_state.alloc_end_called = 1;
> >
> > This is not nice. What happens if grub_xen_p2m_alloc() allocate what
> > is needed and grub_xen_special_alloc() fails?
>
> Then grub_xen_alloc_final will fail resulting in boot failure of the
> new kernel. The memory allocated by the single functions will be freed
> in case a new boot is attempted (patch 1 and 2).
>
> > Maybe grub_xen_p2m_alloc(), grub_xen_special_alloc() and grub_xen_pt_alloc()
> > should check itself that required regions are allocated properly
> > (if (something != NULL)) and do nothing if yes.
>
> Hmm, with grub_xen_reset() doing appropriate cleanups this would be an
> option. I think I'll change it as you are suggesting.
It looks that we can completely avoid that stuff. I think that
grub_xen_alloc_final() should be called conditionally in both
places/cases. That is all.
Daniel
[PATCH v4 01/11] xen: make xen loader callable multiple times, Juergen Gross, 2016/02/22
[PATCH v4 05/11] xen: synchronize xen header, Juergen Gross, 2016/02/22
[PATCH v4 11/11] xen: add capability to load p2m list outside of kernel mapping, Juergen Gross, 2016/02/22
[PATCH v4 06/11] xen: factor out p2m list allocation into separate function, Juergen Gross, 2016/02/22
[PATCH v4 04/11] xen: add elfnote.h to avoid using numbers instead of constants, Juergen Gross, 2016/02/22
[PATCH v4 03/11] xen: reduce number of global variables in xen loader, Juergen Gross, 2016/02/22
[PATCH v4 10/11] xen: modify page table construction, Juergen Gross, 2016/02/22