From: Julien Grall <julien.grall@arm.com>
To: Daniel Kiper <daniel.kiper@oracle.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,
david.vrabel@citrix.com, Jan Beulich <JBeulich@suse.com>,
xen-devel@lists.xenproject.org, qiaowei.ren@intel.com,
gang.wei@intel.com, fu.wei@linaro.org
Subject: Re: [PATCH v6 08/15] x86/efi: create new early memory allocator
Date: Fri, 23 Sep 2016 12:07:14 +0100 [thread overview]
Message-ID: <00201bc6-cb05-d8bd-b6f7-ab6c83ca2058@arm.com> (raw)
In-Reply-To: <20160923105028.GS28753@olila.local.net-space.pl>
On 23/09/16 11:50, Daniel Kiper wrote:
> Hi Julien,
Hi Daniel,
>
> On Thu, Sep 22, 2016 at 06:07:26PM +0100, Julien Grall wrote:
>
> [...]
>
>>> #ifndef CONFIG_ARM
>>> /* Whole x86 ebmalloc stuff. */
>>> ...
>>> #else
>>> void __init free_ebmalloc_unused_mem(void)
>>> {
>>> }
>>> #endif
>>>
>>> and then call free_ebmalloc_unused_mem() from e.g.
>>> xen/arch/arm/setup.c:init_done(). Am I right?
>>
>> Bear in mind that the EFI loader on ARM is standalone. It cannot
>> interact with Xen.
>>
>> The main goal of the EFI stub is to load the different images on the
>> memory and then will jump at the same starting point as when Xen is
>> loaded without EFI. So anything in bss will be zeroed.
>
> AIUI, on ARM EFI we have following call sequence:
> - efi_start(),
> - efi_xen_start(),
> - real_start()
> - ...
> - el2() which zeroes BSS... ;-(((
>
> We had the same situation on x86. So, we moved BSS init just before
> efi_start() call and disabled later zero BSS if we are booted via EFI.
> Could we do the same on ARM? As I can see Jan wish to use ebmalloc on
> ARM too. Does it make sense for you?
The EFI on ARM has been designed to be standalone and disable page
tables, flush the cache before hand and then jump in the startup
beginning of the binary (as it would be done without EFI).
The problem I can see here, is ebmalloc_mem is allocated in bss rather
than in init. I understand this is an optimization, to shrink down the
size of the binary.
But, I am not in favor to start differing in startup code if we have EFI
enabled just for that.
IHMO, anything related to the stub should be in the init section and
therefore will be freed when Xen has finished to boot.
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-09-23 11:07 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-12 20:18 [PATCH v6 00/15] x86: multiboot2 protocol support Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 01/15] x86: properly calculate ELF end of image address Daniel Kiper
2016-09-16 20:43 ` Konrad Rzeszutek Wilk
2016-09-19 11:14 ` Jan Beulich
2016-09-19 13:56 ` Daniel Kiper
2016-09-19 14:52 ` Jan Beulich
2016-09-20 11:43 ` Daniel Kiper
2016-09-20 13:28 ` Jan Beulich
2016-09-20 18:00 ` Daniel Kiper
2016-09-21 9:37 ` Jan Beulich
2016-09-22 11:45 ` Daniel Kiper
2016-09-22 12:02 ` Jan Beulich
2016-09-19 11:18 ` Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 02/15] x86/boot/reloc: create generic alloc and copy functions Daniel Kiper
2016-09-19 11:23 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 03/15] x86/boot/reloc: rename some variables and rearrange code a bit Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 04/15] x86: add multiboot2 protocol support Daniel Kiper
2016-09-19 11:42 ` Jan Beulich
2016-09-21 8:56 ` Daniel Kiper
2016-09-21 9:41 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 05/15] efi: create efi_enabled() Daniel Kiper
2016-09-19 11:58 ` Jan Beulich
2016-09-19 14:27 ` Daniel Kiper
2016-09-19 14:31 ` Wei Liu
2016-09-19 14:57 ` Jan Beulich
2016-09-19 15:38 ` Daniel Kiper
2016-09-19 16:00 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 06/15] x86: allow EFI reboot method neither on EFI platforms Daniel Kiper
2016-09-19 12:01 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 07/15] efi: build xen.gz with EFI code Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 08/15] x86/efi: create new early memory allocator Daniel Kiper
2016-09-19 12:12 ` Jan Beulich
2016-09-19 15:04 ` Daniel Kiper
2016-09-19 15:17 ` Jan Beulich
2016-09-20 9:45 ` Daniel Kiper
2016-09-20 9:57 ` Jan Beulich
2016-09-20 10:52 ` Daniel Kiper
2016-09-20 13:46 ` Jan Beulich
2016-09-20 18:45 ` Daniel Kiper
2016-09-21 9:42 ` Jan Beulich
2016-09-22 10:52 ` Daniel Kiper
2016-09-22 11:25 ` Jan Beulich
2016-09-22 12:07 ` Daniel Kiper
2016-09-22 13:12 ` Jan Beulich
2016-09-22 17:07 ` Julien Grall
2016-09-23 10:50 ` Daniel Kiper
2016-09-23 11:07 ` Julien Grall [this message]
2016-09-23 11:35 ` Daniel Kiper
2016-09-23 11:42 ` Julien Grall
2016-09-23 11:53 ` Daniel Kiper
2016-09-23 14:10 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 09/15] x86: add multiboot2 protocol support for EFI platforms Daniel Kiper
2016-09-19 12:29 ` Jan Beulich
2016-09-19 15:18 ` Daniel Kiper
2016-09-19 15:28 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 10/15] x86/boot: implement early command line parser in C Daniel Kiper
2016-09-19 12:47 ` Jan Beulich
2016-09-19 15:27 ` Daniel Kiper
2016-09-19 16:03 ` Jan Beulich
2016-09-20 9:49 ` Daniel Kiper
2016-09-20 10:05 ` Jan Beulich
2016-09-20 11:31 ` Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 11/15] x86: change default load address from 1 MiB to 2 MiB Daniel Kiper
2016-09-19 12:54 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 12/15] x86/setup: use XEN_IMG_OFFSET instead of Daniel Kiper
2016-09-19 13:00 ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 13/15] x86: make Xen early boot code relocatable Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 14/15] x86/boot: rename sym_phys() to sym_offs() Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 15/15] x86: add multiboot2 protocol support for relocatable images Daniel Kiper
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