[U-Boot] [BUG] simple-bus and rsa-sw with DM_FLAG_PRE_RELOC

[Auer, Lukas]

On Wed, 2019-05-15 at 17:25 +0900, takahiro.akashi at linaro.org wrote:
> On Wed, May 15, 2019 at 08:14:18AM +0000, Auer, Lukas wrote:
> > On Wed, 2019-05-15 at 15:39 +0800, Bin Meng wrote:
> > > On Wed, May 15, 2019 at 3:12 PM AKASHI Takahiro
> > > <takahiro.akashi at linaro.org> wrote:
> > > > On Wed, May 15, 2019 at 02:45:19PM +0800, Bin Meng wrote:
> > > > > On Wed, May 15, 2019 at 1:55 PM AKASHI Takahiro
> > > > > <takahiro.akashi at linaro.org> wrote:
> > > > > > As of v2019.07-rc1,
> > > > > > u-boot does fail to boot without any messages on qemu-arm64 when
> > > > > > configured with qemu_arm64_defconfig plus CONFIG_RSA/RSA_SOFTWARE_EXP.
> > > > > > (Note that RSA_SOFTWARE_EXP also declares itself with DM_FLAG_PRE_RELOC.)
> > > > > > 
> > > > > > By bisecting between v2019.04 and v2019.07, I found that the following
> > > > > > commit triggered this regression:
> > > > > > 
> > > > > >         commit 3a7c45f6a772
> > > > > >         Author: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
> > > > > >         Date:   Wed Apr 10 14:46:07 2019 +0200
> > > > > > 
> > > > > >             simple-bus: add DM_FLAG_PRE_RELOC flag to simple-bus driver
> > > > > > 
> > > > > > What's wrong with this?
> > > > > 
> > > > > I just tested it and it boots for me.
> > > > > 
> > > > > $ make qemu_arm64_defconfig
> > > > > $ make menuconfig
> > > > > adding CONFIG_RSA via "Library routines" -> "Security support" -> "Use
> > > > > RSA Library"
> > > > > $ make
> > > > > 
> > > > > $ qemu-system-aarch64 -machine virt -cpu cortex-a57 -bios u-boot.bin -nographic
> > > > 
> > > > Thank you.
> > > > I have used locally-built qemu, so I will check the configuration of
> > > > my build.
> > > 
> > > FYI
> > > 
> > > $ qemu-system-aarch64 -version
> > > QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.36),
> > > Copyright (c) 2003-2008 Fabrice Bellard
> > > 
> > > I was using Ubuntu 16.04 shipped QEMU packages.
> > > 
> > > Regards,
> > > Bin
> > 
> > The device tree might be different on your build. With this patch, more
> > drivers are probed during the pre-relocation device model. This
> > increases the size requirements of CONFIG_SYS_MALLOC_F_LEN. qemu-arm64
> > uses the default value for CONFIG_SYS_MALLOC_F_LEN, which is likely too
> > small. We had similar problems on the i.MX devices, see [1]. Increasing
> > it should fix the issue.
> > 
> > Thanks,
> > Lukas
> > 
> > [1]: https://patchwork.ozlabs.org/patch/1094974/
> 
> Ah, it was a known issue.
> But is there any better, or more flexible, way to fix that issue?
> It was very difficult for me to find out a clue for root cause.
> 
> Thanks,
> -Takahiro Akashi

One problem is that the serial console is not yet available when the
out of memory error occurs. However with DEBUG_UART configured, U-Boot
should print an error (I did not test this). We could also increase the
default value of CONFIG_SYS_MALLOC_F_LEN, but this might not be
possible on all boards.

You are right, it would be good to have a better way of fixing this,
but I am not sure what the best way of doing that is.

Thanks,
Lukas