| Message ID | 1360365467-25056-10-git-send-email-ben.dooks@codethink.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 8 Feb 2013, Ben Dooks wrote: > Add atag32_to_cpu() function to allow code manipulating ATAGs to deal > with the case where the boot-loader was in little-endian and Linux is > running big-endian. > > Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Acked-by: Nicolas Pitre <nico@linaro.org> > --- > arch/arm/include/uapi/asm/setup.h | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/include/uapi/asm/setup.h b/arch/arm/include/uapi/asm/setup.h > index 979ff40..d74a417 100644 > --- a/arch/arm/include/uapi/asm/setup.h > +++ b/arch/arm/include/uapi/asm/setup.h > @@ -175,13 +175,18 @@ struct tagtable { > > #define tag_member_present(tag,member) \ > ((unsigned long)(&((struct tag *)0L)->member + 1) \ > - <= (tag)->hdr.size * 4) > + <= atag32_to_cpu((tag)->hdr.size) * 4) > > -#define tag_next(t) ((struct tag *)((__u32 *)(t) + (t)->hdr.size)) > +#define tag_next(t) ((struct tag *)((__u32 *)(t) + atag32_to_cpu((t)->hdr.size))) > #define tag_size(type) ((sizeof(struct tag_header) + sizeof(struct type)) >> 2) > > #define for_each_tag(t,base) \ > for (t = base; t->hdr.size; t = tag_next(t)) > > +#ifdef CONFIG_CPU_BE8_BOOT_LE > +#define atag32_to_cpu(x) le32_to_cpu(x) > +#else > +#define atag32_to_cpu(x) x > +#endif > > #endif /* _UAPI__ASMARM_SETUP_H */ > -- > 1.7.10.4 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
On Fri, Feb 08, 2013 at 11:17:39PM +0000, Ben Dooks wrote: > Add atag32_to_cpu() function to allow code manipulating ATAGs to deal > with the case where the boot-loader was in little-endian and Linux is > running big-endian. ... > +#ifdef CONFIG_CPU_BE8_BOOT_LE > +#define atag32_to_cpu(x) le32_to_cpu(x) > +#else > +#define atag32_to_cpu(x) x > +#endif Actually, with a LE kernel, le32_to_cpu() ends up being a no-op too. So I'm wondering if we should do this a different way... Also, this will cause sparse to complain - le32_to_cpu() takes a le32 type not a u32 type. This brings up a whole load of difficulties though: what format are the ATAGs on older BE hardware - I bet it's CPU-endian format there. So, I'm wondering if we should do this: 1. define all tags using a new __atagXX, etc types. 2. always use atagXX_to_cpu() to read these. 3. Implement: #if defined(CONFIG_ATAG_LE) typedef __le32 __atag32; ... #define atag32_to_cpu(x) le32_to_cpu(x) ... #elif defined(CONFIG_ATAG_BE) typedef __be32 __atag32; ... #define atag32_to_cpu(x) be32_to_cpu(x) ... #elif defined(CONFIG_ATAG_NE) typedef __u32 __atag32; ... #define atag32_to_cpu(x) x ... #endif and select the appropriate definition. Obviously, this is a fundamental configuration just like the overall BE/LE configuration of the kernel.
On 09/02/13 12:03, Russell King - ARM Linux wrote: > On Fri, Feb 08, 2013 at 11:17:39PM +0000, Ben Dooks wrote: >> Add atag32_to_cpu() function to allow code manipulating ATAGs to deal >> with the case where the boot-loader was in little-endian and Linux is >> running big-endian. > ... >> +#ifdef CONFIG_CPU_BE8_BOOT_LE >> +#define atag32_to_cpu(x) le32_to_cpu(x) >> +#else >> +#define atag32_to_cpu(x) x >> +#endif > > Actually, with a LE kernel, le32_to_cpu() ends up being a no-op too. So > I'm wondering if we should do this a different way... > > Also, this will cause sparse to complain - le32_to_cpu() takes a le32 > type not a u32 type. Yes, you're right on that. > This brings up a whole load of difficulties though: what format are the > ATAGs on older BE hardware - I bet it's CPU-endian format there. So, > I'm wondering if we should do this: It isn't defined, and I have failed to find any information on it online. I have no idea if the IXP devices ran their boot-loader in big-endian or little-endian format? Input welcome from anyone who can remember. > 1. define all tags using a new __atagXX, etc types. > 2. always use atagXX_to_cpu() to read these. > 3. Implement: > > #if defined(CONFIG_ATAG_LE) > typedef __le32 __atag32; > ... > #define atag32_to_cpu(x) le32_to_cpu(x) > ... > #elif defined(CONFIG_ATAG_BE) > typedef __be32 __atag32; > ... > #define atag32_to_cpu(x) be32_to_cpu(x) > ... > #elif defined(CONFIG_ATAG_NE) > typedef __u32 __atag32; > ... > #define atag32_to_cpu(x) x > ... > #endif > > and select the appropriate definition. Obviously, this is a fundamental > configuration just like the overall BE/LE configuration of the kernel. Ok, should I sort out doing that for the next round of patches? Should the ATAG_xx configurations go into arch/arm/Kconfig or is there somewhere better for them to go?
On Mon, Feb 11, 2013 at 07:15:19PM +0000, Ben Dooks wrote: > It isn't defined, and I have failed to find any information on > it online. I have no idea if the IXP devices ran their boot-loader > in big-endian or little-endian format? It will be native endian, because that's the format which we've supported up to now. >> 1. define all tags using a new __atagXX, etc types. >> 2. always use atagXX_to_cpu() to read these. >> 3. Implement: >> >> #if defined(CONFIG_ATAG_LE) >> typedef __le32 __atag32; >> ... >> #define atag32_to_cpu(x) le32_to_cpu(x) >> ... >> #elif defined(CONFIG_ATAG_BE) >> typedef __be32 __atag32; >> ... >> #define atag32_to_cpu(x) be32_to_cpu(x) >> ... >> #elif defined(CONFIG_ATAG_NE) >> typedef __u32 __atag32; >> ... >> #define atag32_to_cpu(x) x >> ... >> #endif >> >> and select the appropriate definition. Obviously, this is a fundamental >> configuration just like the overall BE/LE configuration of the kernel. > > Ok, should I sort out doing that for the next round of patches? Yes please. > Should the ATAG_xx configurations go into arch/arm/Kconfig or > is there somewhere better for them to go? arch/arm/Kconfig for the time being. I've debated about moving some config options to arch/arm/boot/Kconfig
On 19:15 Mon 11 Feb , Ben Dooks wrote: > On 09/02/13 12:03, Russell King - ARM Linux wrote: > >On Fri, Feb 08, 2013 at 11:17:39PM +0000, Ben Dooks wrote: > >>Add atag32_to_cpu() function to allow code manipulating ATAGs to deal > >>with the case where the boot-loader was in little-endian and Linux is > >>running big-endian. > >... > >>+#ifdef CONFIG_CPU_BE8_BOOT_LE > >>+#define atag32_to_cpu(x) le32_to_cpu(x) > >>+#else > >>+#define atag32_to_cpu(x) x > >>+#endif > > > >Actually, with a LE kernel, le32_to_cpu() ends up being a no-op too. So > >I'm wondering if we should do this a different way... > > > >Also, this will cause sparse to complain - le32_to_cpu() takes a le32 > >type not a u32 type. > > Yes, you're right on that. > > >This brings up a whole load of difficulties though: what format are the > >ATAGs on older BE hardware - I bet it's CPU-endian format there. So, > >I'm wondering if we should do this: > > It isn't defined, and I have failed to find any information on > it online. I have no idea if the IXP devices ran their boot-loader > in big-endian or little-endian format? > > Input welcome from anyone who can remember. I run the ixp in be and pass the atag in be Best Regards, J. > > >1. define all tags using a new __atagXX, etc types. > >2. always use atagXX_to_cpu() to read these. > >3. Implement: > > > >#if defined(CONFIG_ATAG_LE) > >typedef __le32 __atag32; > >... > >#define atag32_to_cpu(x) le32_to_cpu(x) > >... > >#elif defined(CONFIG_ATAG_BE) > >typedef __be32 __atag32; > >... > >#define atag32_to_cpu(x) be32_to_cpu(x) > >... > >#elif defined(CONFIG_ATAG_NE) > >typedef __u32 __atag32; > >... > >#define atag32_to_cpu(x) x > >... > >#endif > > > >and select the appropriate definition. Obviously, this is a fundamental > >configuration just like the overall BE/LE configuration of the kernel. > > Ok, should I sort out doing that for the next round of patches? > > Should the ATAG_xx configurations go into arch/arm/Kconfig or > is there somewhere better for them to go? > > -- > Ben Dooks http://www.codethink.co.uk/ > Senior Engineer Codethink - Providing Genius > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Tue, Feb 12, 2013 at 07:46:36PM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote: > I run the ixp in be > > and pass the atag in be So that would be "native endian" then.
diff --git a/arch/arm/include/uapi/asm/setup.h b/arch/arm/include/uapi/asm/setup.h index 979ff40..d74a417 100644 --- a/arch/arm/include/uapi/asm/setup.h +++ b/arch/arm/include/uapi/asm/setup.h @@ -175,13 +175,18 @@ struct tagtable { #define tag_member_present(tag,member) \ ((unsigned long)(&((struct tag *)0L)->member + 1) \ - <= (tag)->hdr.size * 4) + <= atag32_to_cpu((tag)->hdr.size) * 4) -#define tag_next(t) ((struct tag *)((__u32 *)(t) + (t)->hdr.size)) +#define tag_next(t) ((struct tag *)((__u32 *)(t) + atag32_to_cpu((t)->hdr.size))) #define tag_size(type) ((sizeof(struct tag_header) + sizeof(struct type)) >> 2) #define for_each_tag(t,base) \ for (t = base; t->hdr.size; t = tag_next(t)) +#ifdef CONFIG_CPU_BE8_BOOT_LE +#define atag32_to_cpu(x) le32_to_cpu(x) +#else +#define atag32_to_cpu(x) x +#endif #endif /* _UAPI__ASMARM_SETUP_H */
Add atag32_to_cpu() function to allow code manipulating ATAGs to deal with the case where the boot-loader was in little-endian and Linux is running big-endian. Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> --- arch/arm/include/uapi/asm/setup.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)