[U-Boot] [PATCH] qemu-arm: Add persistent environment support

[Sumit Garg]

Hi Akashi,

On Tue, 27 Nov 2018 at 12:14, AKASHI Takahiro
<takahiro.akashi at linaro.org> wrote:
>
> Sumit,
>
> # I have a similar patch in my local branch :)
>

IIRC, we did sync on this work.

> On Mon, Nov 26, 2018 at 04:50:17PM +0530, Sumit Garg wrote:
> > Currently on qemu-arm platforms environment is kept in RAM. Instead
> > use pflash device 1 to provide persistent environment support across
> > device reset.
> >
> > Also (optionally) provide support for persistent environment across
> > qemu machine OFF/ON using following instructions:
> >
> > - Create envstore.img using qemu-img:
> >     qemu-img create -f raw envstore.img 64M
> > - Add a pflash drive parameter to the command line:
> >     -drive if=pflash,format=raw,index=1,file=envstore.img
> >
> > Signed-off-by: Sumit Garg <sumit.garg at linaro.org>
> > ---
> >  configs/qemu_arm64_defconfig | 7 +++++++
> >  configs/qemu_arm_defconfig   | 7 +++++++
> >  doc/README.qemu-arm          | 6 ++++++
> >  include/configs/qemu-arm.h   | 8 +++++++-
> >  4 files changed, 27 insertions(+), 1 deletion(-)
> >
> > diff --git a/configs/qemu_arm64_defconfig b/configs/qemu_arm64_defconfig
> > index f4502c9..0f13716 100644
> > --- a/configs/qemu_arm64_defconfig
> > +++ b/configs/qemu_arm64_defconfig
> > @@ -29,3 +29,10 @@ CONFIG_USB=y
> >  CONFIG_DM_USB=y
> >  CONFIG_USB_EHCI_HCD=y
> >  CONFIG_USB_EHCI_PCI=y
> > +CONFIG_ENV_IS_IN_FLASH=y
> > +CONFIG_MTD=y
> > +CONFIG_MTD_NOR_FLASH=y
> > +CONFIG_FLASH_CFI_DRIVER=y
>
> This one and
>
> > +CONFIG_CFI_FLASH=y
>
> > +CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
> > +CONFIG_SYS_FLASH_CFI=y
>
> those two are not currently Kconfig parameters.
> So they should not be put in *_defconfig, but in include/configs/*.
> Or it would be better to define them as new Kconfigs?
>

I do see these Kconfigs already defined in drivers/mtd/Kconfig.

> > diff --git a/configs/qemu_arm_defconfig b/configs/qemu_arm_defconfig
> > index acebdc5..b75363e 100644
> > --- a/configs/qemu_arm_defconfig
> > +++ b/configs/qemu_arm_defconfig
> > @@ -29,3 +29,10 @@ CONFIG_USB=y
> >  CONFIG_DM_USB=y
> >  CONFIG_USB_EHCI_HCD=y
> >  CONFIG_USB_EHCI_PCI=y
> > +CONFIG_ENV_IS_IN_FLASH=y
> > +CONFIG_MTD=y
> > +CONFIG_MTD_NOR_FLASH=y
> > +CONFIG_FLASH_CFI_DRIVER=y
> > +CONFIG_CFI_FLASH=y
> > +CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
> > +CONFIG_SYS_FLASH_CFI=y
> > diff --git a/doc/README.qemu-arm b/doc/README.qemu-arm
> > index 2601656..e67bc13 100644
> > --- a/doc/README.qemu-arm
> > +++ b/doc/README.qemu-arm
> > @@ -47,6 +47,12 @@ The minimal QEMU command line to get U-Boot up and running is:
> >  Note that for some odd reason qemu-system-aarch64 needs to be explicitly
> >  told to use a 64-bit CPU or it will boot in 32-bit mode.
> >
> > +Additional persistent U-boot environment support can be added as follows:
> > +- Create envstore.img using qemu-img:
> > +    qemu-img create -f raw envstore.img 64M
> > +- Add a pflash drive parameter to the command line:
> > +    -drive if=pflash,format=raw,index=1,file=envstore.img
> > +
> >  Additional peripherals that have been tested to work in both U-Boot and Linux
> >  can be enabled with the following command line parameters:
> >
> > diff --git a/include/configs/qemu-arm.h b/include/configs/qemu-arm.h
> > index fedc466..83a930b 100644
> > --- a/include/configs/qemu-arm.h
> > +++ b/include/configs/qemu-arm.h
> > @@ -21,7 +21,8 @@
> >  #define CONFIG_SYS_HZ                       1000
> >
> >  /* Environment options */
> > -#define CONFIG_ENV_SIZE                              SZ_64K
> > +#define CONFIG_ENV_ADDR                      0x4000000
> > +#define CONFIG_ENV_SIZE                      SZ_256K
>
> # I'm not sure whether those definitions be enforced for all qemu-arm users.
>
> Do you have any reason to put env region in the second bank?

Yes I thought it would be better to load "envstore.img" on bank #1
separately from u-boot.bin (loaded on bank #0) like we do for
"varstore" while booting UEFI/edk2. This also doesn't change existing
cmdline to use "-bios" option for u-boot.bin and rather provide an
optional cmdline argument to load environment.

Also I have updated ENV_SIZE to be SZ_256K due to minimum erase size
for flash being 256K (sector size).

> If not, I suggest that it be left free for other use.
>

AFAIK, I haven't seen any other usage for flash. If you are aware of
any, please do let me know.

Regards,
Sumit

> Thanks,
> -Takahiro Akashi
>
> >  #define BOOT_TARGET_DEVICES(func) \
> >       func(SCSI, scsi, 0) \
> > @@ -42,4 +43,9 @@
> >
> >  #define CONFIG_SYS_CBSIZE 512
> >
> > +#define CONFIG_SYS_MONITOR_BASE              CONFIG_SYS_TEXT_BASE
> > +#define CONFIG_SYS_FLASH_BASE                0x0
> > +#define CONFIG_SYS_MAX_FLASH_BANKS   2
> > +#define CONFIG_SYS_MAX_FLASH_SECT    256 /* Sector: 256K, Bank: 64M */
> > +
> >  #endif /* __CONFIG_H */
> > --
> > 2.7.4
> >