| Message ID | 1442482345-7679-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Thu, Sep 17, 2015 at 10:32:25AM +0100, Ard Biesheuvel wrote: > In order for a bootloader to be able to decide whether a certain > arm64 kernel image is compatible with the hardware it is running > on, it needs to be able to find out for which page size the kernel > was built. This is necessary, since the architecture does not > mandate support for all page sizes it defines, and the kernel cannot > boot to a state where it can print a diagnostic if it was built for > a page size that is not supported by the hardware. > > So assign two bits in the flags field of the Image header, and set > them according to the build time page size. For backward compatibility, > retain the 0b00 value as 'unspecified'. > > Acked-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> This looks sane to me. FWIW: Acked-by: Mark Rutland <mark.rutland@arm.com> Thanks, Mark. > --- > Documentation/arm64/booting.txt | 3 ++- > arch/arm64/kernel/image.h | 4 +++- > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt > index 1690350f16e7..46056e7d766e 100644 > --- a/Documentation/arm64/booting.txt > +++ b/Documentation/arm64/booting.txt > @@ -104,7 +104,8 @@ Header notes: > - The flags field (introduced in v3.17) is a little-endian 64-bit field > composed as follows: > Bit 0: Kernel endianness. 1 if BE, 0 if LE. > - Bits 1-63: Reserved. > + Bits 1-2: Kernel page size. 0=unspecified, 1=4K, 2=16K, 3=64K > + Bits 3-63: Reserved. > > - When image_size is zero, a bootloader should attempt to keep as much > memory as possible free for use by the kernel immediately after the > diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h > index 8fae0756e175..5def289bda84 100644 > --- a/arch/arm64/kernel/image.h > +++ b/arch/arm64/kernel/image.h > @@ -47,7 +47,9 @@ > #define __HEAD_FLAG_BE 0 > #endif > > -#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) > +#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2) > + > +#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) | (__HEAD_FLAG_PAGE_SIZE << 1) > > /* > * These will output as part of the Image header, which should be little-endian > -- > 1.9.1 >
On 17/09/15 10:32, Ard Biesheuvel wrote: > In order for a bootloader to be able to decide whether a certain > arm64 kernel image is compatible with the hardware it is running > on, it needs to be able to find out for which page size the kernel > was built. This is necessary, since the architecture does not > mandate support for all page sizes it defines, and the kernel cannot > boot to a state where it can print a diagnostic if it was built for > a page size that is not supported by the hardware. > > So assign two bits in the flags field of the Image header, and set > them according to the build time page size. For backward compatibility, > retain the 0b00 value as 'unspecified'. > > Acked-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Ard, I picked this patch based on the our initial discussion on 16K page size series, and added it to the V2 of the series. https://lkml.org/lkml/2015/9/15/716 > --- > Documentation/arm64/booting.txt | 3 ++- > arch/arm64/kernel/image.h | 4 +++- > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt > index 1690350f16e7..46056e7d766e 100644 > --- a/Documentation/arm64/booting.txt > +++ b/Documentation/arm64/booting.txt > @@ -104,7 +104,8 @@ Header notes: > - The flags field (introduced in v3.17) is a little-endian 64-bit field > composed as follows: > Bit 0: Kernel endianness. 1 if BE, 0 if LE. > - Bits 1-63: Reserved. > + Bits 1-2: Kernel page size. 0=unspecified, 1=4K, 2=16K, 3=64K > + Bits 3-63: Reserved. > > - When image_size is zero, a bootloader should attempt to keep as much > memory as possible free for use by the kernel immediately after the > diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h > index 8fae0756e175..5def289bda84 100644 > --- a/arch/arm64/kernel/image.h > +++ b/arch/arm64/kernel/image.h > @@ -47,7 +47,9 @@ > #define __HEAD_FLAG_BE 0 > #endif > > -#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) > +#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2) > + > +#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) | (__HEAD_FLAG_PAGE_SIZE << 1) > FWIW, Tested-by: Suzuki K. Poulose <suzuki.poulose@arm.com> Thanks Suzuki
On 18 September 2015 at 10:17, Suzuki K. Poulose <Suzuki.Poulose@arm.com> wrote: > On 17/09/15 10:32, Ard Biesheuvel wrote: >> >> In order for a bootloader to be able to decide whether a certain >> arm64 kernel image is compatible with the hardware it is running >> on, it needs to be able to find out for which page size the kernel >> was built. This is necessary, since the architecture does not >> mandate support for all page sizes it defines, and the kernel cannot >> boot to a state where it can print a diagnostic if it was built for >> a page size that is not supported by the hardware. >> >> So assign two bits in the flags field of the Image header, and set >> them according to the build time page size. For backward compatibility, >> retain the 0b00 value as 'unspecified'. >> >> Acked-by: Catalin Marinas <catalin.marinas@arm.com> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > > Ard, > > I picked this patch based on the our initial discussion on 16K page size > series, and added it to the V2 of the series. > > https://lkml.org/lkml/2015/9/15/716 > Ah, I missed that, sorry. I don't care which version makes it eventually, > > >> --- >> Documentation/arm64/booting.txt | 3 ++- >> arch/arm64/kernel/image.h | 4 +++- >> 2 files changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/arm64/booting.txt >> b/Documentation/arm64/booting.txt >> index 1690350f16e7..46056e7d766e 100644 >> --- a/Documentation/arm64/booting.txt >> +++ b/Documentation/arm64/booting.txt >> @@ -104,7 +104,8 @@ Header notes: >> - The flags field (introduced in v3.17) is a little-endian 64-bit field >> composed as follows: >> Bit 0: Kernel endianness. 1 if BE, 0 if LE. >> - Bits 1-63: Reserved. >> + Bits 1-2: Kernel page size. 0=unspecified, 1=4K, 2=16K, 3=64K >> + Bits 3-63: Reserved. >> >> - When image_size is zero, a bootloader should attempt to keep as much >> memory as possible free for use by the kernel immediately after the >> diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h >> index 8fae0756e175..5def289bda84 100644 >> --- a/arch/arm64/kernel/image.h >> +++ b/arch/arm64/kernel/image.h >> @@ -47,7 +47,9 @@ >> #define __HEAD_FLAG_BE 0 >> #endif >> >> -#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) >> +#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2) >> + >> +#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) | (__HEAD_FLAG_PAGE_SIZE << >> 1) >> > > FWIW, > > Tested-by: Suzuki K. Poulose <suzuki.poulose@arm.com> > Thank you, Ard.
diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index 1690350f16e7..46056e7d766e 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -104,7 +104,8 @@ Header notes: - The flags field (introduced in v3.17) is a little-endian 64-bit field composed as follows: Bit 0: Kernel endianness. 1 if BE, 0 if LE. - Bits 1-63: Reserved. + Bits 1-2: Kernel page size. 0=unspecified, 1=4K, 2=16K, 3=64K + Bits 3-63: Reserved. - When image_size is zero, a bootloader should attempt to keep as much memory as possible free for use by the kernel immediately after the diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h index 8fae0756e175..5def289bda84 100644 --- a/arch/arm64/kernel/image.h +++ b/arch/arm64/kernel/image.h @@ -47,7 +47,9 @@ #define __HEAD_FLAG_BE 0 #endif -#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) +#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2) + +#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) | (__HEAD_FLAG_PAGE_SIZE << 1) /* * These will output as part of the Image header, which should be little-endian