From: Daniel Kiper <daniel.kiper@oracle.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Juergen Gross <JGross@suse.com>,
sstabellini@kernel.org, andrew.cooper3@citrix.com,
cardoe@cardoe.com, pgnet.dev@gmail.com, ning.sun@intel.com,
julien.grall@arm.com, david.vrabel@citrix.com,
xen-devel@lists.xenproject.org, qiaowei.ren@intel.com,
gang.wei@intel.com, fu.wei@linaro.org
Subject: Re: [PATCH v7 08/14] x86: add multiboot2 protocol support for EFI platforms
Date: Tue, 27 Sep 2016 20:11:24 +0200 [thread overview]
Message-ID: <20160927181124.GJ28753@olila.local.net-space.pl> (raw)
In-Reply-To: <57E9431E02000078001127DB@prv-mh.provo.novell.com>
On Mon, Sep 26, 2016 at 07:47:42AM -0600, Jan Beulich wrote:
> >>> On 23.09.16 at 23:47, <daniel.kiper@oracle.com> wrote:
> > This way Xen can be loaded on EFI platforms using GRUB2 and
> > other boot loaders which support multiboot2 protocol.
> >
> > Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
> > Acked-by: Jan Beulich <jbeulich@suse.com>
> > ---
> > v7 - suggestions/fixes:
> > - do not allocate twice memory for trampoline if we were
> > loaded via multiboot2 protocol on EFI platform,
>
> If you fix bugs not noticed by a reviewer but by yourself, please
> drop all acks/R-b-s covering the code in question. And then I'm
OK.
> afraid I haven't even been able to locate that change - could you
> please point out what you did where?
The change is very subtle. I add trampoline_setup label behind
/* From arch/x86/smpboot.c: start_eip had better be page-aligned! */
xor %cl, %cl
instead of
cmp %ecx,%edx /* compare with BDA value */
cmovb %edx,%ecx /* and use the smaller */
> > + /*
> > + * Initialize BSS (no nasty surprises!).
> > + * It must be done earlier than in BIOS case
> > + * because efi_multiboot2() touches it.
> > + */
> > + lea .startof.(.bss)(%rip),%edi
> > + mov $.sizeof.(.bss),%ecx
> > + shr $3,%ecx
> > + xor %eax,%eax
> > + rep stosq
> > +
> > + pop %rdi
> > +
> > + /*
> > + * efi_multiboot2() is called according to System V AMD64 ABI:
> > + * - IN: %rdi - EFI ImageHandle, %rsi - EFI SystemTable,
> > + * - OUT: %rax - highest usable memory address below 1 MiB;
> > + * memory above this address is reserved for trampoline;
> > + * memory below this address is used for stack and as
> > + * a storage for boot data.
>
> How can you validly use memory below this address? (And I'd like to
Right, I should not do that blindly. As quick fix we can check in efi_arch_process_memory_map()
that chosen memory region has size cfg.size plus let's say 64 KiB. Is it sufficient
for you? However, I think that later (for 4.9?) we should consider what we discussed
here https://lists.xen.org/archives/html/xen-devel/2016-09/msg01424.html
> note that this also changed from v6, and the change to comments
> listed in the v7 section and supposedly suggested by me can't cover
> this, as I don't recall having asked for such an adjustment.)
Ah, sorry about that. I should be more precise.
Daniel
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next prev parent reply other threads:[~2016-09-27 18:11 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-23 21:47 [PATCH v7 00/14] x86: multiboot2 protocol support Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 01/14] x86: move xen ELF end of image to 16 MiB Daniel Kiper
2016-09-26 10:39 ` Jan Beulich
2016-09-26 11:34 ` Daniel Kiper
2016-09-26 12:32 ` Jan Beulich
2016-09-27 17:42 ` Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 02/14] x86: properly calculate xen ELF end of image address Daniel Kiper
2016-09-26 10:45 ` Jan Beulich
2016-09-26 12:06 ` Daniel Kiper
2016-09-26 12:34 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 03/14] x86: add multiboot2 protocol support Daniel Kiper
2016-09-26 13:18 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 04/14] efi: create efi_enabled() Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 05/14] x86: allow EFI reboot method neither on EFI platforms Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 06/14] efi: build xen.gz with EFI code Daniel Kiper
2016-09-23 21:47 ` [PATCH RFC v7 07/14] efi: create new early memory allocator Daniel Kiper
2016-09-23 23:35 ` Julien Grall
2016-09-26 6:53 ` Jan Beulich
2016-09-26 20:01 ` Julien Grall
2016-09-27 8:06 ` Jan Beulich
2016-09-27 23:23 ` Julien Grall
2016-09-26 13:37 ` Jan Beulich
2016-09-27 17:49 ` Daniel Kiper
2016-09-28 8:48 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 08/14] x86: add multiboot2 protocol support for EFI platforms Daniel Kiper
2016-09-26 13:47 ` Jan Beulich
2016-09-27 18:11 ` Daniel Kiper [this message]
2016-09-28 8:57 ` Jan Beulich
2016-09-28 9:39 ` Daniel Kiper
2016-09-28 10:16 ` Jan Beulich
2016-09-26 14:19 ` Andrew Cooper
2016-09-26 14:33 ` Jan Beulich
2016-09-26 14:40 ` Andrew Cooper
2016-09-26 15:12 ` Jan Beulich
2016-09-27 18:21 ` Daniel Kiper
2016-09-28 8:58 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 09/14] x86/boot: implement early command line parser in C Daniel Kiper
2016-09-26 13:49 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 10/14] x86: change default load address from 1 MiB to 2 MiB Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 11/14] x86/setup: use XEN_IMG_OFFSET instead of Daniel Kiper
2016-09-23 21:47 ` [PATCH v7 12/14] x86: make Xen early boot code relocatable Daniel Kiper
2016-09-26 15:03 ` Jan Beulich
2016-09-27 19:55 ` Daniel Kiper
2016-09-28 9:06 ` Jan Beulich
2016-09-28 9:56 ` Daniel Kiper
2016-09-28 10:19 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 13/14] x86/boot: rename sym_phys() to sym_offs() Daniel Kiper
2016-09-26 15:47 ` Jan Beulich
2016-09-23 21:47 ` [PATCH v7 14/14] x86: add multiboot2 protocol support for relocatable images Daniel Kiper
2016-09-26 15:53 ` Jan Beulich
2016-09-27 20:07 ` Daniel Kiper
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