Re: [PATCH 1/5] mips: start.S: Add Octeon boot header compatibility
On 26.10.20 14:42, Daniel Schwierzeck wrote: Am Freitag, den 16.10.2020, 15:08 +0200 schrieb Stefan Roese: Octeon has a specific boot header, when booted via SPI NOR, NAND or MMC. Here the only 2 instructions are allowed in the first few bytes of the image. And these instructions need to be one branch and a nop. This patch adds the necessary nop after the nop, to that the common MIPS image is compatible with this Octeon header. The tool to patch the Octeon boot header into the image will be send in a follow-up patch. Signed-off-by: Stefan Roese Cc: Aaron Williams Cc: Chandrakala Chavva Cc: Daniel Schwierzeck --- arch/mips/cpu/start.S | 8 +++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S index d0c412236d..6de2470cc2 100644 --- a/arch/mips/cpu/start.S +++ b/arch/mips/cpu/start.S @@ -75,8 +75,13 @@ ENTRY(_start) /* U-Boot entry point */ + /* +* Octeon needs special handling here, as the binary might be +* patched to add a boot header for SPI, NAND or MMC booting. Only +* one branch plus nop is allowed here. +*/ I'd prefer a shorter and more imperative comment within one multi-line comment block, e.g. /* * U-Boot entry point. * Do not add instructions to the branch delay slot! Some SoC's * like Octeon might patch the final U-Boot binary at this location * with additional boot headers. */ Even better. Will change in v2. b reset -mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing +nop #if defined(CONFIG_MIPS_INSERT_BOOT_CONFIG) /* @@ -123,6 +128,7 @@ ENTRY(_start) #endif reset: +mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing the extra indentation of one space is only required for instructions in delay slots and needs to be removed. Yes, thanks for catching. Thanks, Stefan
Re: [PATCH 1/5] mips: start.S: Add Octeon boot header compatibility
Am Freitag, den 16.10.2020, 15:08 +0200 schrieb Stefan Roese: > Octeon has a specific boot header, when booted via SPI NOR, NAND or MMC. > Here the only 2 instructions are allowed in the first few bytes of the > image. And these instructions need to be one branch and a nop. This > patch adds the necessary nop after the nop, to that the common MIPS > image is compatible with this Octeon header. > > The tool to patch the Octeon boot header into the image will be send in > a follow-up patch. > > Signed-off-by: Stefan Roese > Cc: Aaron Williams > Cc: Chandrakala Chavva > Cc: Daniel Schwierzeck > --- > arch/mips/cpu/start.S | 8 +++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S > index d0c412236d..6de2470cc2 100644 > --- a/arch/mips/cpu/start.S > +++ b/arch/mips/cpu/start.S > @@ -75,8 +75,13 @@ > > ENTRY(_start) > /* U-Boot entry point */ > + /* > + * Octeon needs special handling here, as the binary might be > + * patched to add a boot header for SPI, NAND or MMC booting. Only > + * one branch plus nop is allowed here. > + */ I'd prefer a shorter and more imperative comment within one multi-line comment block, e.g. /* * U-Boot entry point. * Do not add instructions to the branch delay slot! Some SoC's * like Octeon might patch the final U-Boot binary at this location * with additional boot headers. */ > b reset > - mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing > + nop > > #if defined(CONFIG_MIPS_INSERT_BOOT_CONFIG) > /* > @@ -123,6 +128,7 @@ ENTRY(_start) > #endif > > reset: > + mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing the extra indentation of one space is only required for instructions in delay slots and needs to be removed. > #if __mips_isa_rev >= 6 > mfc0t0, CP0_CONFIG, 5 > and t0, t0, MIPS_CONF5_VP -- - Daniel
Re: [PATCH 1/5] mips: start.S: Add Octeon boot header compatibility
> From: Stefan Roese > Date: Fri, 16 Oct 2020 15:08:46 +0200 > > Octeon has a specific boot header, when booted via SPI NOR, NAND or MMC. > Here the only 2 instructions are allowed in the first few bytes of the > image. And these instructions need to be one branch and a nop. This > patch adds the necessary nop after the nop, to that the common MIPS > image is compatible with this Octeon header. > > The tool to patch the Octeon boot header into the image will be send in > a follow-up patch. Since the moved instruction is no longer in a delay slot, you should probably remove the extra space before the instruction. Cheers, Mark > Signed-off-by: Stefan Roese > Cc: Aaron Williams > Cc: Chandrakala Chavva > Cc: Daniel Schwierzeck > --- > arch/mips/cpu/start.S | 8 +++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S > index d0c412236d..6de2470cc2 100644 > --- a/arch/mips/cpu/start.S > +++ b/arch/mips/cpu/start.S > @@ -75,8 +75,13 @@ > > ENTRY(_start) > /* U-Boot entry point */ > + /* > + * Octeon needs special handling here, as the binary might be > + * patched to add a boot header for SPI, NAND or MMC booting. Only > + * one branch plus nop is allowed here. > + */ > b reset > - mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing > + nop > > #if defined(CONFIG_MIPS_INSERT_BOOT_CONFIG) > /* > @@ -123,6 +128,7 @@ ENTRY(_start) > #endif > > reset: > + mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing > #if __mips_isa_rev >= 6 > mfc0t0, CP0_CONFIG, 5 > and t0, t0, MIPS_CONF5_VP > -- > 2.28.0 > >
