[PATCH 4/5] [ARM] Auto calculate ZRELADDR and provide option for exceptions

Eric Miao eric.miao at canonical.com
Thu Jun 10 05:18:57 EDT 2010 

2010/6/10 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> On Thu, Jun 03, 2010 at 03:36:52PM +0800, Eric Miao wrote:
>> From: Eric Miao <eric.y.miao at gmail.com>
>>
>> Original idea and prototype came from Nicolas Pitre.
>>
>> As long as the zImage is placed within the 256MB range from the
>> start of the memory, ZRELADDR (Address where the decompressed
>> kernel will be placed, usually  == PHYS_OFFSET + TEXT_OFFSET)
> s/  / /
>
>> can be determined at run-time by masking PC with 0xf000_0000.
>>
>> Running through all the Makefile.boot, all those zreladdr-y
>> address == 0x[0-f]000_0000 + TEXT_OFFSET can be determined at
>> run-time.
>>
>> Option CONFIG_AUTO_ZRELADDR and CONFIG_ZRELADDR are introduced,
>> CONFIG_ZRELADDR _must_ be explicitly specified if:
>>
>>  - ((zreladdr-y - TEXT_OFFSET) & ~0xf0000000) != 0, which means
>>    a maksing of PC with 0xf000_0000 will result an incorrect
> s/maksing of/masking/ (note: there are 2 changes)
>
>>    address.
>>
>>  - or the assumption of the zImage being loaded by the boot
>>    loader within 256MB from the start address is simply
>>    incorrect
> Hmmm, this makes the image depending on the bootloader.  Not that nice.

Yes, that's a negative side. And that's why I'm still keeping CONFIG_ZRELADDR
instead of guessing all the time, so platforms where this assumption isn't true
have to build their kernel with this option set correctly.

I've actually discussed this with Nicolas and his opinion is this is some
thing we can afford, e.g. in PC/x86 world, there are already a lot restrictions
on kernel placement.

My original idea is to embed the machine_desc() section into zImage itself
and invent a machine_desc.phys_offset field so that both the zImage header
and the kernel itself will be both happy. There are some patches actually
ready for this, and I can submit them just in case anyone is interested.

>
>>  - or when ZBOOT_ROM is used, where the above assumption is
>>    normally wrong
> So guess based on sp :-)
>
>> List of all Makefile.boot:
>>
>> Hardcoded, and can be auto calculated by masking PC with 0xf000_0000:
>>
>> arch/arm/mach-cns3xxx/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-dove/Makefile.boot:        zreladdr-y   := 0x00008000
>> arch/arm/mach-ebsa110/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-footbridge/Makefile.boot:          zreladdr-y   := 0x00008000
>> arch/arm/mach-integrator/Makefile.boot:          zreladdr-y   := 0x00008000
>> arch/arm/mach-iop13xx/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-iop33x/Makefile.boot:      zreladdr-y   := 0x00008000
>> arch/arm/mach-ixp2000/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-ixp23xx/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-ixp4xx/Makefile.boot:      zreladdr-y   := 0x00008000
>> arch/arm/mach-kirkwood/Makefile.boot:    zreladdr-y   := 0x00008000
>> arch/arm/mach-ks8695/Makefile.boot:      zreladdr-y   := 0x00008000
>> arch/arm/mach-loki/Makefile.boot:        zreladdr-y   := 0x00008000
>> arch/arm/mach-mmp/Makefile.boot:         zreladdr-y   := 0x00008000
>> arch/arm/mach-mv78xx0/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-nomadik/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-nuc93x/Makefile.boot:      zreladdr-y   := 0x00008000
>> arch/arm/mach-ns9xxx/Makefile.boot:      zreladdr-y   := 0x8000
>> arch/arm/mach-orion5x/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-spear3xx/Makefile.boot:      zreladdr-y := 0x00008000
>> arch/arm/mach-spear6xx/Makefile.boot:      zreladdr-y := 0x00008000
>> arch/arm/mach-ux500/Makefile.boot:       zreladdr-y   := 0x00008000
>> arch/arm/mach-versatile/Makefile.boot:           zreladdr-y   := 0x00008000
>> arch/arm/mach-w90x900/Makefile.boot:     zreladdr-y   := 0x00008000
>> arch/arm/mach-msm/Makefile.boot:         zreladdr-y   := 0x10008000
>> arch/arm/mach-omap1/Makefile.boot:       zreladdr-y   := 0x10008000
>> arch/arm/mach-rpc/Makefile.boot:         zreladdr-y   := 0x10008000
>> arch/arm/mach-s5p6440/Makefile.boot:     zreladdr-y   := 0x20008000
>> arch/arm/mach-s5p6442/Makefile.boot:     zreladdr-y   := 0x20008000
>> arch/arm/mach-s5pc100/Makefile.boot:     zreladdr-y   := 0x20008000
>> arch/arm/mach-s5pv210/Makefile.boot:     zreladdr-y   := 0x20008000
>> arch/arm/mach-s3c2410/Makefile.boot:     zreladdr-y   := 0x30008000
>> arch/arm/mach-s3c2410/Makefile.boot:     zreladdr-y   := 0x30108000
>> arch/arm/mach-stmp378x/Makefile.boot:    zreladdr-y   := 0x40008000
>> arch/arm/mach-stmp37xx/Makefile.boot:    zreladdr-y   := 0x40008000
>> arch/arm/mach-s3c64xx/Makefile.boot:     zreladdr-y   := 0x50008000
>> arch/arm/mach-vexpress/Makefile.boot:    zreladdr-y   := 0x60008000
>> arch/arm/mach-mx25/Makefile.boot:        zreladdr-y   := 0x80008000
>> arch/arm/mach-mx3/Makefile.boot:         zreladdr-y   := 0x80008000
>> arch/arm/mach-netx/Makefile.boot:        zreladdr-y   := 0x80008000
>> arch/arm/mach-omap2/Makefile.boot:       zreladdr-y   := 0x80008000
>> arch/arm/mach-pnx4008/Makefile.boot:     zreladdr-y   := 0x80008000
>> arch/arm/mach-mx5/Makefile.boot:         zreladdr-y   := 0x90008000
>> arch/arm/mach-mxc91231/Makefile.boot:    zreladdr-y   := 0x90008000
>> arch/arm/mach-iop32x/Makefile.boot:      zreladdr-y   := 0xa0008000
>> arch/arm/mach-pxa/Makefile.boot:         zreladdr-y   := 0xa0008000
>> arch/arm/mach-lh7a40x/Makefile.boot:     zreladdr-y   := 0xc0008000
>> arch/arm/mach-clps711x/Makefile.boot:    zreladdr-y   := 0xc0028000
>> arch/arm/mach-aaec2000/Makefile.boot:    zreladdr-y   := 0xf0008000
>> arch/arm/mach-l7200/Makefile.boot:       zreladdr-y   := 0xf0008000
>>
>> Depends on other options/macros, but still can be auto calculated by
>> masking PC with 0xf000_0000:
>>
>> arch/arm/mach-bcmring/Makefile.boot:     zreladdr-y   := $(CONFIG_BCM_ZRELADDR)
>> * refer to arch/arm/configs/bcmring_defconfig:CONFIG_BCM_ZRELADDR=0x8000
>> arch/arm/mach-h720x/Makefile.boot:       zreladdr-$(CONFIG_ARCH_H720X) := 0x40008000
>> arch/arm/mach-shmobile/Makefile.boot:    zreladdr-y   := $(__ZRELADDR)
>> * __ZRELADDR depends on CONFIG_MEMORY_START
>> arch/arm/configs/ap4evb_defconfig:    CONFIG_MEMORY_START=0x40000000 (SH7372)
>> arch/arm/configs/g3evm_defconfig:     CONFIG_MEMORY_START=0x50000000 (SH7367)
>> arch/arm/configs/g4evm_defconfig:     CONFIG_MEMORY_START=0x40000000 (SH7377)
>>
>> arch/arm/mach-at91/Makefile.boot:        zreladdr-y   := 0x70008000 (CONFIG_ARCH_AT91CAP9)
>> arch/arm/mach-at91/Makefile.boot:        zreladdr-y   := 0x70008000 (CONFIG_ARCH_AT91SAM9G45)
>> arch/arm/mach-at91/Makefile.boot:        zreladdr-y   := 0x20008000 (CONFIG_ARCH_AT91)
>> arch/arm/mach-davinci/Makefile.boot:     zreladdr-y   := 0xc0008000 (CONFIG_ARCH_DAVINCI_DA8XX)
>> arch/arm/mach-davinci/Makefile.boot:     zreladdr-y   := 0x80008000 (!CONFIG_ARCH_DAVINCI_DA8XX)
>> arch/arm/mach-ep93xx/Makefile.boot:      zreladdr-$(CONFIG_EP93XX_SDCE3_SYNC_PHYS_OFFSET)     := 0x00008000
>> arch/arm/mach-ep93xx/Makefile.boot:      zreladdr-$(CONFIG_EP93XX_SDCE0_PHYS_OFFSET)          := 0xc0008000
>> arch/arm/mach-ep93xx/Makefile.boot:      zreladdr-$(CONFIG_EP93XX_SDCE1_PHYS_OFFSET)          := 0xd0008000
>> arch/arm/mach-ep93xx/Makefile.boot:      zreladdr-$(CONFIG_EP93XX_SDCE2_PHYS_OFFSET)          := 0xe0008000
>> arch/arm/mach-ep93xx/Makefile.boot:      zreladdr-$(CONFIG_EP93XX_SDCE3_ASYNC_PHYS_OFFSET)    := 0xf0008000
>> arch/arm/mach-gemini/Makefile.boot:      zreladdr-y   := 0x00008000 (CONFIG_GEMINI_MEM_SWAP)
>> arch/arm/mach-gemini/Makefile.boot:      zreladdr-y   := 0x10008000 (!CONFIG_GEMINI_MEM_SWAP)
>> arch/arm/mach-mx2/Makefile.boot:         zreladdr-$(CONFIG_MACH_MX21) := 0xC0008000
>> arch/arm/mach-mx2/Makefile.boot:         zreladdr-$(CONFIG_MACH_MX27) := 0xA0008000
>> arch/arm/mach-realview/Makefile.boot:    zreladdr-y   := 0x70008000 (CONFIG_REALVIEW_HIGH_PHYS_OFFSET)
>> arch/arm/mach-realview/Makefile.boot:    zreladdr-y   := 0x00008000 (CONFIG_REALVIEW_HIGH_PHYS_OFFSET)
>> arch/arm/mach-sa1100/Makefile.boot:      zreladdr-y   := 0xc0008000
>> arch/arm/mach-sa1100/Makefile.boot:      zreladdr-$(CONFIG_SA1111) := 0xc0208000
>>
>> Machines where ZRELADDR cannot be auto calcuated:
>>
>> arch/arm/mach-mx1/Makefile.boot:         zreladdr-y   := 0x08008000
>> arch/arm/mach-shark/Makefile.boot:       zreladdr-y   := 0x08008000
>> arch/arm/mach-u300/Makefile.boot:        zreladdr-y   := 0x28E08000
>> arch/arm/mach-u300/Makefile.boot:        zreladdr-y   := 0x48008000
> I care about mx1, so I would prefer using 0xf8000000.

Fair enough actually. And my guess of the u300 architecture is the phys
offset actually starts from 0x2800_0000 or 0x4800_0000 which is also
covered by 0xf800_0000. And I think u300 can actually get rid of those
inconsistent addresses by other means though we all know it might be
suffering from the communication processor side of the memory allocation.

>
> What do you think about requiring r4 to be set to physoffset as I did in
> my series?

My only concern is to impose less restrictions on the boot loaders.
And zImage is only one of the possible headers we may have:

 * vmlinux can actually directly booted into as long as it's placed at the
   right place
 * uImage, with zImage or vmlinux (raw or compressed) encapsulated
 * zImage
 * xipImage
 * bootpImage

I'd really like to separate the guess work into two parts so they don't
have dependencies.

> This way zImage would already know PHYSOFFSET and so didn't
> need to guess ZRELADDR.  OK, until most bootloaders are fixed we need
> to guess, too.  But at least this would provide a way to stop guessing
> wrong for the affected platforms.
>

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