[U-Boot] [EXT] Re: [ARMv8] kernel entry point
Tom Rini
trini at konsulko.com
Fri May 10 15:05:31 UTC 2019
On Fri, May 10, 2019 at 02:40:52PM +0000, Pankaj Bansal wrote:
> Hi Tom,
>
> Further update.
> I asked this question to linux maintainer, and he pointed out that load address that I am using is not correct.
> The linux load address should be (2 MB aligned + text_offset).
> The text_offset can be obtained from first 64 bytes in linux Image.
> For our use case it comes out to be 0x81080000.
>
> One thing that I wonder though is, that I did not receive any warning or error from uboot about load address.
> Can such warning/error be added in uboot ?
I think you need to debug what's going on more, now that you've gotten
that far. We should already be moving the Image to 2MB aligned +
text_offset with booti.
>
> Regards,
> Pankaj Bansal
>
> > -----Original Message-----
> > From: Pankaj Bansal
> > Sent: Tuesday, 7 May, 2019 03:48 PM
> > To: 'Tom Rini' <trini at konsulko.com>
> > Cc: 'u-boot at lists.denx.de' <u-boot at lists.denx.de>; Prabhakar Kushwaha
> > <prabhakar.kushwaha at nxp.com>; Varun Sethi <V.Sethi at nxp.com>
> > Subject: RE: [EXT] Re: [ARMv8] kernel entry point
> >
> > On further testing I tried to boot the linux from ATF (https://github.com/ARM-
> > software/arm-trusted-firmware)
> > Without using u-boot
> > Even with ATF, the linux is not able to boot from 0x81000000, but is able to boot
> > from 0x80080000 Seems like linux issue and not u-boot issue.
> > I will ask this question in linux community.
> >
> > Regards,
> > Pankaj Bansal
> >
> > > -----Original Message-----
> > > From: Pankaj Bansal
> > > Sent: Tuesday, 7 May, 2019 08:30 AM
> > > To: 'Tom Rini' <trini at konsulko.com>
> > > Cc: 'u-boot at lists.denx.de' <u-boot at lists.denx.de>; Prabhakar Kushwaha
> > > <prabhakar.kushwaha at nxp.com>; Varun Sethi <V.Sethi at nxp.com>
> > > Subject: RE: [EXT] Re: [ARMv8] kernel entry point
> > >
> > > Hi Tom,
> > >
> > > In order to determine whether linux entry point has been called or
> > > not, I put a loop in kernel:
> > >
> > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index
> > > 261f3f88364c..dea6cb8baa6a 100644
> > > --- a/arch/arm64/kernel/head.S
> > > +++ b/arch/arm64/kernel/head.S
> > > @@ -80,6 +80,7 @@ _head:
> > > * its opcode forms the magic "MZ" signature required by UEFI.
> > > */
> > > add x13, x18, #0x16
> > > + b .
> > > b stext
> > > #else
> > > b stext // branch to kernel start, magic
> > >
> > > This loop is being executed when I boot the kernel, but after I jump
> > > over this loop there is no log.
> > > Does it mean that bootloader is working fine, it's the linux that is
> > > not able to boot from 0x81000000 (0x80000000 being the RAM starting
> > address) ?
> > >
> > > Regards,
> > > Pankaj Bansal
> > >
> > > > -----Original Message-----
> > > > From: Pankaj Bansal
> > > > Sent: Monday, 6 May, 2019 07:04 PM
> > > > To: Tom Rini <trini at konsulko.com>
> > > > Cc: u-boot at lists.denx.de; Prabhakar Kushwaha
> > > > <prabhakar.kushwaha at nxp.com>; Varun Sethi <V.Sethi at nxp.com>
> > > > Subject: RE: [EXT] Re: [ARMv8] kernel entry point
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Tom Rini <trini at konsulko.com>
> > > > > Sent: Monday, 6 May, 2019 06:59 PM
> > > > > To: Pankaj Bansal <pankaj.bansal at nxp.com>
> > > > > Cc: u-boot at lists.denx.de; Prabhakar Kushwaha
> > > > > <prabhakar.kushwaha at nxp.com>; Varun Sethi <V.Sethi at nxp.com>
> > > > > Subject: [EXT] Re: [ARMv8] kernel entry point
> > > > >
> > > > > On Mon, May 06, 2019 at 01:06:45PM +0000, Pankaj Bansal wrote:
> > > > >
> > > > > > Hi Tom et. Al,
> > > > > >
> > > > > > I am facing an issue while booting linux on our ARMv8 based platform.
> > > > > > In our platform DDR address starts from 0x80000000.
> > > > > > If I make the linux kernel entry point 0x80080000 in mkimage,
> > > > > > then linux boots
> > > > > fine.
> > > > > > BUT, if I make the linux image entry point as 0x81000000 in
> > > > > > mkimage, the
> > > > > kernel doesn't boot.
> > > > > >
> > > > > > => bootm 0xa0000000 - 0xa1000000 ## Current stack ends at
> > > > > > 0xfbb24400 ## Booting kernel from Legacy Image at
> > > > > a0000000 ...
> > > > > > Image Name: linux
> > > > > > Image Type: AArch64 Linux Kernel Image (gzip compressed)
> > > > > > Data Size: 9110442 Bytes = 8.7 MiB
> > > > > > Load Address: 81000000
> > > > > > Entry Point: 81000000
> > > > > > Verifying Checksum ... OK
> > > > > > ## Flattened Device Tree blob at a1000000
> > > > > > Booting using the fdt blob at 0xa1000000
> > > > > > Uncompressing Kernel Image ... OK
> > > > > > using: FDT
> > > > > > reserving fdt memory region: addr=80000000 size=10000
> > > > > > Loading Device Tree to 000000009fff6000, end 000000009ffff2f8 ...
> > > > > > OK ## Transferring control to Linux (at address 81000000)...
> > > > > >
> > > > > > Starting kernel ...
> > > > > >
> > > > > > I get no kernel logs after this. I am failing to understand why.
> > > > > > Can you please help me in debugging this issue?
> > > > >
> > > > > Why are you using a legacy image on AArch64 at all? You should be
> > > > > using either the kernel Image (and booti) or a FIT image.
> > > >
> > > > This issue is coming even if I use FIT image.
> > > >
> > > > => bootm 0xa0000000#lx2160ardb
> > > > ## Current stack ends at 0xfbb24400 ## Loading kernel from FIT Image
> > > > at
> > > > a0000000 ...
> > > > Using 'lx2160ardb' configuration
> > > > Trying 'kernel' kernel subimage
> > > > Description: ARM64 Kernel
> > > > Type: Kernel Image
> > > > Compression: gzip compressed
> > > > Data Start: 0xa00000d0
> > > > Data Size: 9110442 Bytes = 8.7 MiB
> > > > Architecture: AArch64
> > > > OS: Linux
> > > > Load Address: 0x81000000
> > > > Entry Point: 0x81000000
> > > > Hash algo: crc32
> > > > Hash value: 39f59891
> > > > Verifying Hash Integrity ... crc32+ OK ## Loading ramdisk from
> > > > FIT Image at
> > > > a0000000 ...
> > > > Using 'lx2160ardb' configuration
> > > > Trying 'initrd' ramdisk subimage
> > > > Description: initrd for arm64
> > > > Type: RAMDisk Image
> > > > Compression: uncompressed
> > > > Data Start: 0xa08b055c
> > > > Data Size: 29171975 Bytes = 27.8 MiB
> > > > Architecture: AArch64
> > > > OS: Linux
> > > > Load Address: 0x00000000
> > > > Entry Point: 0x00000000
> > > > Hash algo: crc32
> > > > Hash value: 23038325
> > > > Verifying Hash Integrity ... crc32+ OK ## Loading fdt from FIT
> > > > Image at
> > > > a0000000 ...
> > > > Using 'lx2160ardb' configuration
> > > > Trying 'lx2160ardb-dtb' fdt subimage
> > > > Description: lx2160ardb-dtb
> > > > Type: Flat Device Tree
> > > > Compression: uncompressed
> > > > Data Start: 0xa249071c
> > > > Data Size: 25337 Bytes = 24.7 KiB
> > > > Architecture: AArch64
> > > > Load Address: 0x90000000
> > > > Hash algo: crc32
> > > > Hash value: 8e4d595f
> > > > Verifying Hash Integrity ... crc32+ OK
> > > > Loading fdt from 0xa249071c to 0x90000000
> > > > Booting using the fdt blob at 0x90000000
> > > > Uncompressing Kernel Image ... OK
> > > > using: FDT
> > > > reserving fdt memory region: addr=80000000 size=10000
> > > > Loading Device Tree to 000000009fff6000, end 000000009ffff2f8 ...
> > > > OK ## Transferring control to Linux (at address 81000000)...
> > > >
> > > > Starting kernel ...
> > > >
> > > >
> > > > >
> > > > > --
> > > > > Tom
> Date: Fri, 10 May 2019 14:36:37 +0000
> From: Pankaj Bansal <pankaj.bansal at nxp.com>
> To: Mark Rutland <mark.rutland at arm.com>
> CC: Catalin Marinas <catalin.marinas at arm.com>, Will Deacon
> <will.deacon at arm.com>, Ard Biesheuvel <ard.biesheuvel at linaro.org>, Wasim
> Khan <wasim.khan at nxp.com>, Varun Sethi <V.Sethi at nxp.com>,
> "linux-arm-kernel at lists.infradead.org"
> <linux-arm-kernel at lists.infradead.org>
> Subject: RE: [ARMv8] kernel entry point
>
> Hi Mark,
>
> > -----Original Message-----
> > From: Mark Rutland <mark.rutland at arm.com>
> > Sent: Friday, 10 May, 2019 07:11 PM
> > To: Pankaj Bansal <pankaj.bansal at nxp.com>
> > Cc: Catalin Marinas <catalin.marinas at arm.com>; Will Deacon
> > <will.deacon at arm.com>; Ard Biesheuvel <ard.biesheuvel at linaro.org>; Wasim
> > Khan <wasim.khan at nxp.com>; Varun Sethi <V.Sethi at nxp.com>; linux-arm-
> > kernel at lists.infradead.org
> > Subject: Re: [ARMv8] kernel entry point
> >
> > Hi Pankaj,
> >
> > On Fri, May 10, 2019 at 01:24:55PM +0000, Pankaj Bansal wrote:
> > > + Ard,
> > > Hi Ard,
> > >
> > > Can you please check below mail? We are not able to boot linux loading
> > > Image at 16MB offset (0x81000000) from DDR start address (0x80000000)
> > > I have tested with both u-boot as well as atf.
> > >
> > > This issue is occurring with latest kernel (5.1) Image. If I revert
> > > kernel code to commit a7f8de168ace ("arm64: allow kernel Image to be
> > > loaded anywhere in physical memory "), then this issue doesn't occur.
> >
> > That commit allows the 2MiB base to be arbitrary, but the text_offset must still
> > be taken into account. That's all documented in:
> >
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel
> > .org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Ftree%
> > 2FDocumentation%2Farm64%2Fbooting.txt%3Fh%3Dv5.1%23n125&data=
> > 02%7C01%7Cpankaj.bansal%40nxp.com%7C045f77d8202040db896108d6d54d1
> > 5f2%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636930924443311
> > 148&sdata=nOHlA67bfSc21hS0kTnHGJ%2BqxSa2KvAGnRPq7%2FEQgmg%3
> > D&reserved=0
> >
> > .. where we say:
> >
> > | The Image must be placed text_offset bytes from a 2MB aligned base
> > | address anywhere in usable system RAM and called there. The region
> > | between the 2 MB aligned base address and the start of the image has
> > | no special significance to the kernel, and may be used for other purposes.
> > | At least image_size bytes from the start of the image must be free for
> > | use by the kernel.
> >
> > ... and where text_offset is defined in the Image header:
> >
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel
> > .org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Ftree%
> > 2FDocumentation%2Farm64%2Fbooting.txt%3Fh%3Dv5.1%23n73&data=0
> > 2%7C01%7Cpankaj.bansal%40nxp.com%7C045f77d8202040db896108d6d54d15
> > f2%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6369309244433111
> > 48&sdata=Zw2JQ176V6cFXz%2BFcS1uJuYkCZUISjHI%2Bb3HNnkf30k%3D&a
> > mp;reserved=0
> >
> > On a contemporary defconfig kernel, text_offset is 0x80000, so
> > 0x81000000 is not a valid address to load the kernel at.
> >
> > I suspect that things will work if you load your kernel at 0x81080000.
>
> Thank you for this tip. It worked.
>
> >
> > I would strongly recommend you use a bootloader that parses the kernel Image
> > header, and respects text_offset automatically.
>
> I am using u-boot. I don't know if uboot takes into account text_offset in kernel Image header.
> I don't think it's there, otherwise uboot would have given an error to respect the load address requirements.
> I will ask uboot maintainer if such checks (load address = 2MB aligned + text_offset) can be added in uboot.
> Thanks again for your help.
>
> >
> > Thanks,
> > Mark.
> >
> > >
> > > Do you know why the support of "loading kernel Image anywhere in
> > > memory" has been removed in latest kernel ?
> > >
> > > Regards,
> > > Pankaj Bansal
> > >
> > > > -----Original Message-----
> > > > From: Pankaj Bansal
> > > > Sent: Tuesday, 7 May, 2019 04:03 PM
> > > > To: 'Catalin Marinas' <catalin.marinas at arm.com>; 'Will Deacon'
> > > > <will.deacon at arm.com>
> > > > Cc: 'linux-arm-kernel at lists.infradead.org' <linux-arm-
> > > > kernel at lists.infradead.org>; Varun Sethi <V.Sethi at nxp.com>
> > > > Subject: [ARMv8] kernel entry point
> > > >
> > > > Hi Catalin/Will et. Al,
> > > >
> > > > I am s/w engineer from NXP India Pvt. Ltd.
> > > > I am facing an issue while booting linux on our ARMv8 based platform.
> > > > In our platform DDR address starts from 0x80000000.
> > > > If I load kernel image @ address 0x80080000 and then try to boot
> > > > linux image from this address, then linux is booting fine.
> > > > BUT if I load kernel image @ address 0x81000000 and then try to boot
> > > > linux image from this address, then linux is not booting.
> > > > I have tried to boot linux using u-boot as well as arm trusted firmware.
> > > > Linux is not booting with either of these if the linux load address is
> > 0x81000000.
> > > >
> > > > I get no kernel logs like "[ 0.000000] Booting Linux on physical CPU 0x0"
> > > >
> > > > The linux version that I am using is 4.14.53 Can you please help me
> > > > in debugging this issue?
> > > >
> > > > Regards,
> > > > Pankaj Bansal
> > >
> > > _______________________________________________
> > > linux-arm-kernel mailing list
> > > linux-arm-kernel at lists.infradead.org
> > > https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists
> > > .infradead.org%2Fmailman%2Flistinfo%2Flinux-arm-
> > kernel&data=02%7C0
> > >
> > 1%7Cpankaj.bansal%40nxp.com%7C045f77d8202040db896108d6d54d15f2%7C
> > 686ea
> > >
> > 1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636930924443311148&sda
> > ta=Ykm
> > > rBwDOYYLdrOtWFDeBxY2on3xwBP%2F8O1seKm9aiio%3D&reserved=0
--
Tom
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