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From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: James Morse <james.morse@arm.com>
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	dhowells@redhat.com, vgoyal@redhat.com,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	dyoung@redhat.com, bhe@redhat.com, arnd@arndb.de,
	ard.biesheuvel@linaro.org, bhsharma@redhat.com,
	kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 03/11] arm64: kexec_file: invoke the kernel without purgatory
Date: Fri, 18 May 2018 15:22:49 +0900	[thread overview]
Message-ID: <20180518062248.GK2737@linaro.org> (raw)
In-Reply-To: <fbd2c6c6-be20-a9fa-0303-e4448225df18@arm.com>

James,

On Tue, May 15, 2018 at 05:15:52PM +0100, James Morse wrote:
> Hi Akashi,
> 
> On 15/05/18 05:45, AKASHI Takahiro wrote:
> > On Fri, May 11, 2018 at 06:03:49PM +0100, James Morse wrote:
> >> On 07/05/18 06:22, AKASHI Takahiro wrote:
> >>> On Tue, May 01, 2018 at 06:46:06PM +0100, James Morse wrote:
> >>>> On 25/04/18 07:26, AKASHI Takahiro wrote:
> >>>>> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> >>>>> index f76ea92dff91..f7dbba00be10 100644
> >>>>> --- a/arch/arm64/kernel/machine_kexec.c
> >>>>> +++ b/arch/arm64/kernel/machine_kexec.c
> >>>>> @@ -205,10 +205,17 @@ void machine_kexec(struct kimage *kimage)
> >>
> >>>>>  	cpu_soft_restart(kimage != kexec_crash_image,
> >>>>> -		reboot_code_buffer_phys, kimage->head, kimage->start, 0);
> >>>>> +		reboot_code_buffer_phys, kimage->head, kimage->start,
> >>>>> +#ifdef CONFIG_KEXEC_FILE
> >>>>> +				kimage->purgatory_info.purgatory_buf ?
> >>>>> +						0 : kimage->arch.dtb_mem);
> >>>>> +#else
> >>>>> +				0);
> >>>>> +#endif
> >>
> >>
> >>>> purgatory_buf seems to only be set in kexec_purgatory_setup_kbuf(), called from
> >>>> kexec_load_purgatory(), which we don't use. How does this get a value?
> >>>>
> >>>> Would it be better to always use kimage->arch.dtb_mem, and ensure that is 0 for
> >>>> regular kexec (as we can't know where the dtb is)? (image_arg may then be a
> >>>> better name).
> >>>
> >>> The problem is arch.dtb_mem is currently defined only if CONFIG_KEXEC_FILE.
> >>
> >> I thought it was ARCH_HAS_KIMAGE_ARCH, which we can define all the time if
> >> that's what we want.
> >>
> >>
> >>> So I would like to
> >>> - merge this patch with patch#8
> >>> - change the condition
> >>>         #ifdef CONFIG_KEXEC_FILE
> >>>        				kimage->file_mode ? kimage->arch.dtb_mem : 0);

We don't need "kimage->file_mode ?" since arch.dtb_mem is 0 if !file_mode.

> >>>         #else
> >>>         			0);
> >>>         #endif
> >>
> >> If we can avoid even this #ifdef by always having kimage->arch, I'd prefer that.
> >> If we do that 'dtb_mem' would need some thing that indicates its for kexec_file,
> >> as kexec has a DTB too, we just don't know where it is...
> > 
> > OK, but I want to have a minimum of kexec.arch always exist.
> 
> I'm curious, why? Its 32bytes that is allocated a maximum of twice.

I believe that I'm a stingy minimalist :)


> (my questions on what needs to go in there were because it looked like a third
> user was missing...)
> 
> 
> > How about this?
> >
> > | struct kimage_arch {
> > | 	phys_addr_t dtb_mem;
> > | #ifdef CONFIG_KEXEC_FILE
> 
> #ifdef in structs just breeds more #ifdefs, as the code that accesses those
> members has to be behind the same set of conditions.
> 
> Given this, I prefer the #ifdefs around cpu_soft_restart() as it doesn't force
> us to add more #ifdefs later.

OK

> For either option without purgatory_info:
> Reviewed-by: James Morse <james.morse@arm.com>

Thanks,
-Takahiro AKASHI

> 
> Thanks,
> 
> James

  reply	other threads:[~2018-05-18  6:22 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25  6:26 [PATCH v9 00/11] arm64: kexec: add kexec_file_load() support AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 01/11] asm-generic: add kexec_file_load system call to unistd.h AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 02/11] kexec_file: make kexec_image_post_load_cleanup_default() global AKASHI Takahiro
2018-04-28  9:45   ` Dave Young
2018-05-01 17:46   ` James Morse
2018-05-07  4:40     ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 03/11] arm64: kexec_file: invoke the kernel without purgatory AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  5:22     ` AKASHI Takahiro
2018-05-11 17:03       ` James Morse
2018-05-15  4:45         ` AKASHI Takahiro
2018-05-15 16:15           ` James Morse
2018-05-18  6:22             ` AKASHI Takahiro [this message]
2018-04-25  6:26 ` [PATCH v9 04/11] arm64: kexec_file: allocate memory walking through memblock list AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  5:59     ` AKASHI Takahiro
2018-05-15  4:35       ` AKASHI Takahiro
2018-05-15 16:17         ` James Morse
2018-05-17  2:10       ` Baoquan He
2018-05-17  2:15         ` Baoquan He
2018-05-17 18:04           ` James Morse
2018-05-18  1:37             ` Baoquan He
2018-05-18  5:07               ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 05/11] arm64: kexec_file: load initrd and device-tree AKASHI Takahiro
2018-05-15 16:20   ` James Morse
2018-05-18  7:11     ` AKASHI Takahiro
2018-05-18  7:42       ` AKASHI Takahiro
2018-05-18 15:59         ` James Morse
2018-04-25  6:26 ` [PATCH v9 06/11] arm64: kexec_file: allow for loading Image-format kernel AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  7:21     ` AKASHI Takahiro
2018-05-11 17:07       ` James Morse
2018-05-15  5:13         ` AKASHI Takahiro
2018-05-15 17:14           ` James Morse
2018-05-21  9:32             ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 07/11] arm64: kexec_file: add crash dump support AKASHI Takahiro
2018-05-15 17:11   ` James Morse
2018-05-16  8:34     ` James Morse
2018-05-18  9:58       ` AKASHI Takahiro
2018-05-16 10:06     ` James Morse
2018-05-18  9:50       ` AKASHI Takahiro
2018-05-18 10:39     ` AKASHI Takahiro
2018-05-18 16:00       ` James Morse
2018-05-21  9:46         ` AKASHI Takahiro
2018-05-15 17:12   ` James Morse
2018-05-18 15:35     ` Rob Herring
2018-05-21 10:14       ` AKASHI Takahiro
2018-05-24 14:25         ` Rob Herring
2018-04-25  6:26 ` [PATCH v9 08/11] arm64: enable KEXEC_FILE config AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 09/11] include: pe.h: remove message[] from mz header definition AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 10/11] arm64: kexec_file: add kernel signature verification support AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 11/11] arm64: kexec_file: add kaslr support AKASHI Takahiro

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