* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-26 18:57 ` Nicolas Pitre
0 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-26 18:57 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, 26 Jan 2015, Tony Lindgren wrote:
> * Pali Roh?r <pali.rohar@gmail.com> [150126 08:26]:
> > On Monday 26 January 2015 17:14:55 Tony Lindgren wrote:
> > > * Pali Roh?r <pali.rohar@gmail.com> [150123 14:39]:
> > > > On Friday 23 January 2015 22:39:55 Pali Roh?r wrote:
> > > > > Hello,
> > > > >
> > > > > when I boot zImage with appended DT n900 in qemu
> > > > > fdt_open_into() function called from file
> > > > > arch/arm/boot/compressed/atags_to_fdt.c (in function
> > > > > atags_to_fdt) always returns -FDT_ERR_NOSPACE.
> > > > >
> > > > > It means that all ATAGS (including cmdline arguments)
> > > > > passed by bootloader are ignored.
> > > > >
> > > > > On real n900 device I see that booted DT version also
> > > > > ignore cmdline arguments from bootloader. I cannot debug
> > > > > decompress code on real device, but I think it is same
> > > > > problem as in qemu.
> > > >
> > > > Looks like this quick patch is fixing above problem:
> > > >
> > > > diff --git a/arch/arm/boot/compressed/head.S
> > > > b/arch/arm/boot/compressed/head.S index 68be901..4a7d75b
> > > > 100644
> > > > --- a/arch/arm/boot/compressed/head.S
> > > > +++ b/arch/arm/boot/compressed/head.S
> > > > @@ -268,7 +268,7 @@ restart: adr r0, LC0
> > > >
> > > > * area. No GOT fixup has occurred yet, but none of
> > the
> > > > * code we're about to call uses any global variable.
> > > >
> > > > */
> > > >
> > > > - add sp, sp, #0x10000
> > > > + add sp, sp, #0x20000
> > > >
> > > > stmfd sp!, {r0-r3, ip, lr}
> > > > mov r0, r8
> > > > mov r1, r6
> > > >
> > > > @@ -289,7 +289,7 @@ restart: adr r0, LC0
> > > >
> > > > bleq atags_to_fdt
> > > >
> > > > ldmfd sp!, {r0-r3, ip, lr}
> > > >
> > > > - sub sp, sp, #0x10000
> > > > + sub sp, sp, #0x20000
> > > >
> > > > #endif
> > > >
> > > > mov r8, r6 @ use the appended device tree
> > >
> > > Nico, got any ideas about this one? This seems like a
> > > regression somewhere..
> > >
> > > Regards,
> > >
> > > Tony
> >
> > $ du -b arch/arm/boot/dts/omap3-n900.dtb
> > 70212 arch/arm/boot/dts/omap3-n900.dtb
> >
> > $ echo $((0x10000))
> > 65536
> >
> > I would say, problem is because omap3-n900 binary DT is too large
I agree.
> OK if that's the case, then your patch makes sense to me. It also
> seems we can have the temporary stack be larger than the initial
> stack just for atags_to_fdt.
The stack size isn't the issue, but rather its location. We need to
position it away from the DT data. The DT size is known and we could
use that, plus some room for the insertion of new data coming from the
ATAG conversion.
Something like the following would be a more robust solution:
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 68be901759..89718de9dd 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -263,16 +263,37 @@ restart: adr r0, LC0
* OK... Let's do some funky business here.
* If we do have a DTB appended to zImage, and we do have
* an ATAG list around, we want the later to be translated
- * and folded into the former here. To be on the safe side,
- * let's temporarily move the stack away into the malloc
- * area. No GOT fixup has occurred yet, but none of the
- * code we're about to call uses any global variable.
+ * and folded into the former here. No GOT fixup has occurred
+ * yet, but none of the code we're about to call uses any
+ * global variable.
*/
- add sp, sp, #0x10000
+
+ /* Get the initial DTB size */
+ ldr r5, [r6, #4]
+#ifndef __ARMEB__
+ /* convert to little endian */
+ eor r1, r5, r5, ror #16
+ bic r1, r1, #0x00ff0000
+ mov r5, r5, ror #8
+ eor r5, r5, r1, lsr #8
+#endif
+ /* 50% DTB growth should be good enough */
+ add r5, r5, r5, lsr #1
+ /* preserve 64-bit alignment */
+ add r5, r5, #7
+ bic r5, r5, #7
+ /* clamp to 32KB min and 1MB max */
+ movs r1, r5, lsr #15
+ moveq r5, #(1 << 15)
+ movs r1, r5, lsr #20
+ movne r5, #(1 << 20)
+
+ /* Temporarily relocate the stack past the DTB work space */
+ add sp, sp, r5
stmfd sp!, {r0-r3, ip, lr}
mov r0, r8
mov r1, r6
- sub r2, sp, r6
+ mov r2, r5
bl atags_to_fdt
/*
@@ -285,11 +306,11 @@ restart: adr r0, LC0
bic r0, r0, #1
add r0, r0, #0x100
mov r1, r6
- sub r2, sp, r6
+ mov r2, r5
bleq atags_to_fdt
ldmfd sp!, {r0-r3, ip, lr}
- sub sp, sp, #0x10000
+ sub sp, sp, r5
#endif
mov r8, r6 @ use the appended device tree
@@ -306,7 +327,7 @@ restart: adr r0, LC0
subs r1, r5, r1
addhi r9, r9, r1
- /* Get the dtb's size */
+ /* Get the current DTB size */
ldr r5, [r6, #4]
#ifndef __ARMEB__
/* convert r5 (dtb size) to little endian */
^ permalink raw reply related [flat|nested] 43+ messages in thread* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-26 18:57 ` Nicolas Pitre
@ 2015-01-26 21:48 ` Pavel Machek
-1 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-26 21:48 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
Hi!
> > > $ du -b arch/arm/boot/dts/omap3-n900.dtb
> > > 70212 arch/arm/boot/dts/omap3-n900.dtb
> > >
> > > $ echo $((0x10000))
> > > 65536
> > >
> > > I would say, problem is because omap3-n900 binary DT is too large
>
> I agree.
>
> > OK if that's the case, then your patch makes sense to me. It also
> > seems we can have the temporary stack be larger than the initial
> > stack just for atags_to_fdt.
>
> The stack size isn't the issue, but rather its location. We need to
> position it away from the DT data. The DT size is known and we could
> use that, plus some room for the insertion of new data coming from the
> ATAG conversion.
>
> Something like the following would be a more robust solution:
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901759..89718de9dd 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -263,16 +263,37 @@ restart: adr r0, LC0
> * OK... Let's do some funky business here.
> * If we do have a DTB appended to zImage, and we do have
> * an ATAG list around, we want the later to be translated
> - * and folded into the former here. To be on the safe side,
> - * let's temporarily move the stack away into the malloc
> - * area. No GOT fixup has occurred yet, but none of the
> - * code we're about to call uses any global variable.
> + * and folded into the former here. No GOT fixup has occurred
> + * yet, but none of the code we're about to call uses any
> + * global variable.
> */
> - add sp, sp, #0x10000
> +
> + /* Get the initial DTB size */
> + ldr r5, [r6, #4]
> +#ifndef __ARMEB__
> + /* convert to little endian */
> + eor r1, r5, r5, ror #16
> + bic r1, r1, #0x00ff0000
> + mov r5, r5, ror #8
> + eor r5, r5, r1, lsr #8
> +#endif
> + /* 50% DTB growth should be good enough */
> + add r5, r5, r5, lsr #1
> + /* preserve 64-bit alignment */
> + add r5, r5, #7
> + bic r5, r5, #7
> + /* clamp to 32KB min and 1MB max */
> + movs r1, r5, lsr #15
> + moveq r5, #(1 << 15)
> + movs r1, r5, lsr #20
> + movne r5, #(1 << 20)
Dunno. Would it be easier/simpler to just use 1MB, always? Do we
support machines with <16MB RAM?
Best regards,
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-26 21:48 ` Pavel Machek
0 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-26 21:48 UTC (permalink / raw)
To: linux-arm-kernel
Hi!
> > > $ du -b arch/arm/boot/dts/omap3-n900.dtb
> > > 70212 arch/arm/boot/dts/omap3-n900.dtb
> > >
> > > $ echo $((0x10000))
> > > 65536
> > >
> > > I would say, problem is because omap3-n900 binary DT is too large
>
> I agree.
>
> > OK if that's the case, then your patch makes sense to me. It also
> > seems we can have the temporary stack be larger than the initial
> > stack just for atags_to_fdt.
>
> The stack size isn't the issue, but rather its location. We need to
> position it away from the DT data. The DT size is known and we could
> use that, plus some room for the insertion of new data coming from the
> ATAG conversion.
>
> Something like the following would be a more robust solution:
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901759..89718de9dd 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -263,16 +263,37 @@ restart: adr r0, LC0
> * OK... Let's do some funky business here.
> * If we do have a DTB appended to zImage, and we do have
> * an ATAG list around, we want the later to be translated
> - * and folded into the former here. To be on the safe side,
> - * let's temporarily move the stack away into the malloc
> - * area. No GOT fixup has occurred yet, but none of the
> - * code we're about to call uses any global variable.
> + * and folded into the former here. No GOT fixup has occurred
> + * yet, but none of the code we're about to call uses any
> + * global variable.
> */
> - add sp, sp, #0x10000
> +
> + /* Get the initial DTB size */
> + ldr r5, [r6, #4]
> +#ifndef __ARMEB__
> + /* convert to little endian */
> + eor r1, r5, r5, ror #16
> + bic r1, r1, #0x00ff0000
> + mov r5, r5, ror #8
> + eor r5, r5, r1, lsr #8
> +#endif
> + /* 50% DTB growth should be good enough */
> + add r5, r5, r5, lsr #1
> + /* preserve 64-bit alignment */
> + add r5, r5, #7
> + bic r5, r5, #7
> + /* clamp to 32KB min and 1MB max */
> + movs r1, r5, lsr #15
> + moveq r5, #(1 << 15)
> + movs r1, r5, lsr #20
> + movne r5, #(1 << 20)
Dunno. Would it be easier/simpler to just use 1MB, always? Do we
support machines with <16MB RAM?
Best regards,
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-26 21:48 ` Pavel Machek
@ 2015-01-27 0:06 ` Nicolas Pitre
-1 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 0:06 UTC (permalink / raw)
To: Pavel Machek
Cc: Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
On Mon, 26 Jan 2015, Pavel Machek wrote:
> Hi!
>
> > > > $ du -b arch/arm/boot/dts/omap3-n900.dtb
> > > > 70212 arch/arm/boot/dts/omap3-n900.dtb
> > > >
> > > > $ echo $((0x10000))
> > > > 65536
> > > >
> > > > I would say, problem is because omap3-n900 binary DT is too large
> >
> > I agree.
> >
> > > OK if that's the case, then your patch makes sense to me. It also
> > > seems we can have the temporary stack be larger than the initial
> > > stack just for atags_to_fdt.
> >
> > The stack size isn't the issue, but rather its location. We need to
> > position it away from the DT data. The DT size is known and we could
> > use that, plus some room for the insertion of new data coming from the
> > ATAG conversion.
> >
> > Something like the following would be a more robust solution:
> >
> > diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> > index 68be901759..89718de9dd 100644
> > --- a/arch/arm/boot/compressed/head.S
> > +++ b/arch/arm/boot/compressed/head.S
> > @@ -263,16 +263,37 @@ restart: adr r0, LC0
> > * OK... Let's do some funky business here.
> > * If we do have a DTB appended to zImage, and we do have
> > * an ATAG list around, we want the later to be translated
> > - * and folded into the former here. To be on the safe side,
> > - * let's temporarily move the stack away into the malloc
> > - * area. No GOT fixup has occurred yet, but none of the
> > - * code we're about to call uses any global variable.
> > + * and folded into the former here. No GOT fixup has occurred
> > + * yet, but none of the code we're about to call uses any
> > + * global variable.
> > */
> > - add sp, sp, #0x10000
> > +
> > + /* Get the initial DTB size */
> > + ldr r5, [r6, #4]
> > +#ifndef __ARMEB__
> > + /* convert to little endian */
> > + eor r1, r5, r5, ror #16
> > + bic r1, r1, #0x00ff0000
> > + mov r5, r5, ror #8
> > + eor r5, r5, r1, lsr #8
> > +#endif
> > + /* 50% DTB growth should be good enough */
> > + add r5, r5, r5, lsr #1
> > + /* preserve 64-bit alignment */
> > + add r5, r5, #7
> > + bic r5, r5, #7
> > + /* clamp to 32KB min and 1MB max */
> > + movs r1, r5, lsr #15
> > + moveq r5, #(1 << 15)
> > + movs r1, r5, lsr #20
> > + movne r5, #(1 << 20)
>
> Dunno. Would it be easier/simpler to just use 1MB, always? Do we
> support machines with <16MB RAM?
If people are used to put other things relatively close to the kernel
image like, say, some initrd image, then I'd prefer to be more
conservative and avoid spreading out too much.
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 0:06 ` Nicolas Pitre
0 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 0:06 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, 26 Jan 2015, Pavel Machek wrote:
> Hi!
>
> > > > $ du -b arch/arm/boot/dts/omap3-n900.dtb
> > > > 70212 arch/arm/boot/dts/omap3-n900.dtb
> > > >
> > > > $ echo $((0x10000))
> > > > 65536
> > > >
> > > > I would say, problem is because omap3-n900 binary DT is too large
> >
> > I agree.
> >
> > > OK if that's the case, then your patch makes sense to me. It also
> > > seems we can have the temporary stack be larger than the initial
> > > stack just for atags_to_fdt.
> >
> > The stack size isn't the issue, but rather its location. We need to
> > position it away from the DT data. The DT size is known and we could
> > use that, plus some room for the insertion of new data coming from the
> > ATAG conversion.
> >
> > Something like the following would be a more robust solution:
> >
> > diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> > index 68be901759..89718de9dd 100644
> > --- a/arch/arm/boot/compressed/head.S
> > +++ b/arch/arm/boot/compressed/head.S
> > @@ -263,16 +263,37 @@ restart: adr r0, LC0
> > * OK... Let's do some funky business here.
> > * If we do have a DTB appended to zImage, and we do have
> > * an ATAG list around, we want the later to be translated
> > - * and folded into the former here. To be on the safe side,
> > - * let's temporarily move the stack away into the malloc
> > - * area. No GOT fixup has occurred yet, but none of the
> > - * code we're about to call uses any global variable.
> > + * and folded into the former here. No GOT fixup has occurred
> > + * yet, but none of the code we're about to call uses any
> > + * global variable.
> > */
> > - add sp, sp, #0x10000
> > +
> > + /* Get the initial DTB size */
> > + ldr r5, [r6, #4]
> > +#ifndef __ARMEB__
> > + /* convert to little endian */
> > + eor r1, r5, r5, ror #16
> > + bic r1, r1, #0x00ff0000
> > + mov r5, r5, ror #8
> > + eor r5, r5, r1, lsr #8
> > +#endif
> > + /* 50% DTB growth should be good enough */
> > + add r5, r5, r5, lsr #1
> > + /* preserve 64-bit alignment */
> > + add r5, r5, #7
> > + bic r5, r5, #7
> > + /* clamp to 32KB min and 1MB max */
> > + movs r1, r5, lsr #15
> > + moveq r5, #(1 << 15)
> > + movs r1, r5, lsr #20
> > + movne r5, #(1 << 20)
>
> Dunno. Would it be easier/simpler to just use 1MB, always? Do we
> support machines with <16MB RAM?
If people are used to put other things relatively close to the kernel
image like, say, some initrd image, then I'd prefer to be more
conservative and avoid spreading out too much.
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-26 18:57 ` Nicolas Pitre
@ 2015-01-27 13:37 ` Pavel Machek
-1 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-27 13:37 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
> > > I would say, problem is because omap3-n900 binary DT is too large
>
> I agree.
>
> > OK if that's the case, then your patch makes sense to me. It also
> > seems we can have the temporary stack be larger than the initial
> > stack just for atags_to_fdt.
>
> The stack size isn't the issue, but rather its location. We need to
> position it away from the DT data. The DT size is known and we could
> use that, plus some room for the insertion of new data coming from the
> ATAG conversion.
>
> Something like the following would be a more robust solution:
Tested-by: Pavel Machek <pavel@ucw.cz>
(Note, that in 3.19 dts for n900 got too big, so we are actually
triggering old bugs. That means that this is a regression fix, and
should go in ASAP).
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901759..89718de9dd 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -263,16 +263,37 @@ restart: adr r0, LC0
> * OK... Let's do some funky business here.
> * If we do have a DTB appended to zImage, and we do have
> * an ATAG list around, we want the later to be translated
> - * and folded into the former here. To be on the safe side,
> - * let's temporarily move the stack away into the malloc
> - * area. No GOT fixup has occurred yet, but none of the
> - * code we're about to call uses any global variable.
> + * and folded into the former here. No GOT fixup has occurred
> + * yet, but none of the code we're about to call uses any
> + * global variable.
> */
> - add sp, sp, #0x10000
> +
> + /* Get the initial DTB size */
> + ldr r5, [r6, #4]
> +#ifndef __ARMEB__
> + /* convert to little endian */
> + eor r1, r5, r5, ror #16
> + bic r1, r1, #0x00ff0000
> + mov r5, r5, ror #8
> + eor r5, r5, r1, lsr #8
> +#endif
> + /* 50% DTB growth should be good enough */
> + add r5, r5, r5, lsr #1
> + /* preserve 64-bit alignment */
> + add r5, r5, #7
> + bic r5, r5, #7
> + /* clamp to 32KB min and 1MB max */
> + movs r1, r5, lsr #15
> + moveq r5, #(1 << 15)
> + movs r1, r5, lsr #20
> + movne r5, #(1 << 20)
> +
> + /* Temporarily relocate the stack past the DTB work space */
> + add sp, sp, r5
> stmfd sp!, {r0-r3, ip, lr}
> mov r0, r8
> mov r1, r6
> - sub r2, sp, r6
> + mov r2, r5
> bl atags_to_fdt
>
> /*
> @@ -285,11 +306,11 @@ restart: adr r0, LC0
> bic r0, r0, #1
> add r0, r0, #0x100
> mov r1, r6
> - sub r2, sp, r6
> + mov r2, r5
> bleq atags_to_fdt
>
> ldmfd sp!, {r0-r3, ip, lr}
> - sub sp, sp, #0x10000
> + sub sp, sp, r5
> #endif
>
> mov r8, r6 @ use the appended device tree
> @@ -306,7 +327,7 @@ restart: adr r0, LC0
> subs r1, r5, r1
> addhi r9, r9, r1
>
> - /* Get the dtb's size */
> + /* Get the current DTB size */
> ldr r5, [r6, #4]
> #ifndef __ARMEB__
> /* convert r5 (dtb size) to little endian */
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 13:37 ` Pavel Machek
0 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-27 13:37 UTC (permalink / raw)
To: linux-arm-kernel
> > > I would say, problem is because omap3-n900 binary DT is too large
>
> I agree.
>
> > OK if that's the case, then your patch makes sense to me. It also
> > seems we can have the temporary stack be larger than the initial
> > stack just for atags_to_fdt.
>
> The stack size isn't the issue, but rather its location. We need to
> position it away from the DT data. The DT size is known and we could
> use that, plus some room for the insertion of new data coming from the
> ATAG conversion.
>
> Something like the following would be a more robust solution:
Tested-by: Pavel Machek <pavel@ucw.cz>
(Note, that in 3.19 dts for n900 got too big, so we are actually
triggering old bugs. That means that this is a regression fix, and
should go in ASAP).
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 68be901759..89718de9dd 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -263,16 +263,37 @@ restart: adr r0, LC0
> * OK... Let's do some funky business here.
> * If we do have a DTB appended to zImage, and we do have
> * an ATAG list around, we want the later to be translated
> - * and folded into the former here. To be on the safe side,
> - * let's temporarily move the stack away into the malloc
> - * area. No GOT fixup has occurred yet, but none of the
> - * code we're about to call uses any global variable.
> + * and folded into the former here. No GOT fixup has occurred
> + * yet, but none of the code we're about to call uses any
> + * global variable.
> */
> - add sp, sp, #0x10000
> +
> + /* Get the initial DTB size */
> + ldr r5, [r6, #4]
> +#ifndef __ARMEB__
> + /* convert to little endian */
> + eor r1, r5, r5, ror #16
> + bic r1, r1, #0x00ff0000
> + mov r5, r5, ror #8
> + eor r5, r5, r1, lsr #8
> +#endif
> + /* 50% DTB growth should be good enough */
> + add r5, r5, r5, lsr #1
> + /* preserve 64-bit alignment */
> + add r5, r5, #7
> + bic r5, r5, #7
> + /* clamp to 32KB min and 1MB max */
> + movs r1, r5, lsr #15
> + moveq r5, #(1 << 15)
> + movs r1, r5, lsr #20
> + movne r5, #(1 << 20)
> +
> + /* Temporarily relocate the stack past the DTB work space */
> + add sp, sp, r5
> stmfd sp!, {r0-r3, ip, lr}
> mov r0, r8
> mov r1, r6
> - sub r2, sp, r6
> + mov r2, r5
> bl atags_to_fdt
>
> /*
> @@ -285,11 +306,11 @@ restart: adr r0, LC0
> bic r0, r0, #1
> add r0, r0, #0x100
> mov r1, r6
> - sub r2, sp, r6
> + mov r2, r5
> bleq atags_to_fdt
>
> ldmfd sp!, {r0-r3, ip, lr}
> - sub sp, sp, #0x10000
> + sub sp, sp, r5
> #endif
>
> mov r8, r6 @ use the appended device tree
> @@ -306,7 +327,7 @@ restart: adr r0, LC0
> subs r1, r5, r1
> addhi r9, r9, r1
>
> - /* Get the dtb's size */
> + /* Get the current DTB size */
> ldr r5, [r6, #4]
> #ifndef __ARMEB__
> /* convert r5 (dtb size) to little endian */
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 13:37 ` Pavel Machek
@ 2015-01-27 15:16 ` Nicolas Pitre
-1 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 15:16 UTC (permalink / raw)
To: Pavel Machek
Cc: Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> > > > I would say, problem is because omap3-n900 binary DT is too large
> >
> > I agree.
> >
> > > OK if that's the case, then your patch makes sense to me. It also
> > > seems we can have the temporary stack be larger than the initial
> > > stack just for atags_to_fdt.
> >
> > The stack size isn't the issue, but rather its location. We need to
> > position it away from the DT data. The DT size is known and we could
> > use that, plus some room for the insertion of new data coming from the
> > ATAG conversion.
> >
> > Something like the following would be a more robust solution:
>
> Tested-by: Pavel Machek <pavel@ucw.cz>
>
> (Note, that in 3.19 dts for n900 got too big, so we are actually
> triggering old bugs. That means that this is a regression fix, and
> should go in ASAP).
It is queued here:
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 15:16 ` Nicolas Pitre
0 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 15:16 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> > > > I would say, problem is because omap3-n900 binary DT is too large
> >
> > I agree.
> >
> > > OK if that's the case, then your patch makes sense to me. It also
> > > seems we can have the temporary stack be larger than the initial
> > > stack just for atags_to_fdt.
> >
> > The stack size isn't the issue, but rather its location. We need to
> > position it away from the DT data. The DT size is known and we could
> > use that, plus some room for the insertion of new data coming from the
> > ATAG conversion.
> >
> > Something like the following would be a more robust solution:
>
> Tested-by: Pavel Machek <pavel@ucw.cz>
>
> (Note, that in 3.19 dts for n900 got too big, so we are actually
> triggering old bugs. That means that this is a regression fix, and
> should go in ASAP).
It is queued here:
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 15:16 ` Nicolas Pitre
@ 2015-01-27 15:26 ` Pali Rohár
-1 siblings, 0 replies; 43+ messages in thread
From: Pali Rohár @ 2015-01-27 15:26 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Pavel Machek, Tony Lindgren, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
[-- Attachment #1: Type: Text/Plain, Size: 1311 bytes --]
On Tuesday 27 January 2015 16:16:24 Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > > > I would say, problem is because omap3-n900 binary DT
> > > > > is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to
> > > > me. It also seems we can have the temporary stack be
> > > > larger than the initial stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location.
> > > We need to position it away from the DT data. The DT
> > > size is known and we could use that, plus some room for
> > > the insertion of new data coming from the ATAG
> > > conversion.
> >
> > > Something like the following would be a more robust
solution:
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are
> > actually triggering old bugs. That means that this is a
> > regression fix, and should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id
> =8294/1
>
>
> Nicolas
I tested your patch and fdt_open_into() does not return error
FDT_ERR_NOSPACE anymore. It is working. So you can add my
Tested-by: Pali Rohár <pali.rohar@gmail.com>
--
Pali Rohár
pali.rohar@gmail.com
[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 198 bytes --]
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 15:26 ` Pali Rohár
0 siblings, 0 replies; 43+ messages in thread
From: Pali Rohár @ 2015-01-27 15:26 UTC (permalink / raw)
To: linux-arm-kernel
On Tuesday 27 January 2015 16:16:24 Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > > > I would say, problem is because omap3-n900 binary DT
> > > > > is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to
> > > > me. It also seems we can have the temporary stack be
> > > > larger than the initial stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location.
> > > We need to position it away from the DT data. The DT
> > > size is known and we could use that, plus some room for
> > > the insertion of new data coming from the ATAG
> > > conversion.
> >
> > > Something like the following would be a more robust
solution:
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are
> > actually triggering old bugs. That means that this is a
> > regression fix, and should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id
> =8294/1
>
>
> Nicolas
I tested your patch and fdt_open_into() does not return error
FDT_ERR_NOSPACE anymore. It is working. So you can add my
Tested-by: Pali Roh?r <pali.rohar@gmail.com>
--
Pali Roh?r
pali.rohar at gmail.com
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 15:16 ` Nicolas Pitre
@ 2015-01-27 15:26 ` Tony Lindgren
-1 siblings, 0 replies; 43+ messages in thread
From: Tony Lindgren @ 2015-01-27 15:26 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Pavel Machek, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott
* Nicolas Pitre <nicolas.pitre@linaro.org> [150127 07:19]:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> >
> > > > > I would say, problem is because omap3-n900 binary DT is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to me. It also
> > > > seems we can have the temporary stack be larger than the initial
> > > > stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location. We need to
> > > position it away from the DT data. The DT size is known and we could
> > > use that, plus some room for the insertion of new data coming from the
> > > ATAG conversion.
> > >
> > > Something like the following would be a more robust solution:
> >
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Thanks for fixing that one!
Regards,
Tony
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 15:26 ` Tony Lindgren
0 siblings, 0 replies; 43+ messages in thread
From: Tony Lindgren @ 2015-01-27 15:26 UTC (permalink / raw)
To: linux-arm-kernel
* Nicolas Pitre <nicolas.pitre@linaro.org> [150127 07:19]:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> >
> > > > > I would say, problem is because omap3-n900 binary DT is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to me. It also
> > > > seems we can have the temporary stack be larger than the initial
> > > > stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location. We need to
> > > position it away from the DT data. The DT size is known and we could
> > > use that, plus some room for the insertion of new data coming from the
> > > ATAG conversion.
> > >
> > > Something like the following would be a more robust solution:
> >
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Thanks for fixing that one!
Regards,
Tony
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 15:16 ` Nicolas Pitre
@ 2015-01-27 17:53 ` Russell King - ARM Linux
-1 siblings, 0 replies; 43+ messages in thread
From: Russell King - ARM Linux @ 2015-01-27 17:53 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Pavel Machek, Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, linux-arm-kernel, Laura Abbott
On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Irrespective of that patch, I commented on another thread (about adding
the serial number to DT):
| How about something a little more radical.
|
| Rather than trying to squeeze various ATAGs into DT, why don't we add a
| standard ATAG to contain the DT and pass that through into the kernel.
| This is IMHO how we _should_ have done the ATAG compatibility from the
| start.
|
| That means we could get rid of most of the libfdt in the decompressor,
| and instead resolve the differences in the kernel.
That would allow us to get rid of all the FDT compatibility code in the
decompressor, and when we encounter these special ATAGs, we can deal with
them in the kernel instead of having to mess around with the DT. I'd
also assume (although I haven't checked) that it would be much easier to
add additional DT properties in the kernel environment, rather than in
the rather restrictive decompressor environment.
We'd need to be careful about how we deal with the atags vs DT. I'd
suggest (as above) that we have a tag which points at the DT in
physical memory, and its size, and pre-scan the atag list for that.
When we find it, we kick off the DT based stuff as we would normally
do, and follow it with a parse of the atags. This would cause the
atags to override whatever is in the DT, which afaics is the behaviour
that we actually want.
We could augment that with code to update DT too so that we can export
just the DT based information to kexec'd kernels.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 17:53 ` Russell King - ARM Linux
0 siblings, 0 replies; 43+ messages in thread
From: Russell King - ARM Linux @ 2015-01-27 17:53 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Irrespective of that patch, I commented on another thread (about adding
the serial number to DT):
| How about something a little more radical.
|
| Rather than trying to squeeze various ATAGs into DT, why don't we add a
| standard ATAG to contain the DT and pass that through into the kernel.
| This is IMHO how we _should_ have done the ATAG compatibility from the
| start.
|
| That means we could get rid of most of the libfdt in the decompressor,
| and instead resolve the differences in the kernel.
That would allow us to get rid of all the FDT compatibility code in the
decompressor, and when we encounter these special ATAGs, we can deal with
them in the kernel instead of having to mess around with the DT. I'd
also assume (although I haven't checked) that it would be much easier to
add additional DT properties in the kernel environment, rather than in
the rather restrictive decompressor environment.
We'd need to be careful about how we deal with the atags vs DT. I'd
suggest (as above) that we have a tag which points at the DT in
physical memory, and its size, and pre-scan the atag list for that.
When we find it, we kick off the DT based stuff as we would normally
do, and follow it with a parse of the atags. This would cause the
atags to override whatever is in the DT, which afaics is the behaviour
that we actually want.
We could augment that with code to update DT too so that we can export
just the DT based information to kexec'd kernels.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 17:53 ` Russell King - ARM Linux
@ 2015-01-27 18:50 ` Nicolas Pitre
-1 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 18:50 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Pavel Machek, Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, linux-arm-kernel, Laura Abbott
On Tue, 27 Jan 2015, Russell King - ARM Linux wrote:
> On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> > On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > triggering old bugs. That means that this is a regression fix, and
> > > should go in ASAP).
> >
> > It is queued here:
> > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
>
> Irrespective of that patch, I commented on another thread (about adding
> the serial number to DT):
>
> | How about something a little more radical.
> |
> | Rather than trying to squeeze various ATAGs into DT, why don't we add a
> | standard ATAG to contain the DT and pass that through into the kernel.
> | This is IMHO how we _should_ have done the ATAG compatibility from the
> | start.
> |
> | That means we could get rid of most of the libfdt in the decompressor,
> | and instead resolve the differences in the kernel.
>
> That would allow us to get rid of all the FDT compatibility code in the
> decompressor, and when we encounter these special ATAGs, we can deal with
> them in the kernel instead of having to mess around with the DT. I'd
> also assume (although I haven't checked) that it would be much easier to
> add additional DT properties in the kernel environment, rather than in
> the rather restrictive decompressor environment.
Well...
I was initially against any ATAG-to-DT compatibility at all. IMHO the
"right" solution is to update the bootloader.
However people complained that updating the bootloader wasn't possible.
I therefore suggested they go with a shim layer I termed the "impedance
matcher" acting like an intermediate boot stage converting their (often
unofficial and out-of-tree) ATAGs into proper DT nodes. Some people did
exactly that and it works wonderfully for them. It also works
wonderfully for kernel maintenance as the platform specific tweaks are
kept out of the kernel tree.
Still, that wasn't good enough for some cases as the move to DT
regressed some platforms that just used to work before. Concatenating a
DTB to zImage was tolerable but installing an additional shim layer was
too much. Hence the ATAG-to-DT compat code in the decompressor. This
was meant to smooth things around the transition to DT, etc. After all,
those devices with non-replaceable bootloaders where shim layers are not
possible should get out of commission eventually?
> We'd need to be careful about how we deal with the atags vs DT. I'd
> suggest (as above) that we have a tag which points at the DT in
> physical memory, and its size, and pre-scan the atag list for that.
> When we find it, we kick off the DT based stuff as we would normally
> do, and follow it with a parse of the atags. This would cause the
> atags to override whatever is in the DT, which afaics is the behaviour
> that we actually want.
Maybe. However that would be yet another scheme for supporting legacy
platforms with locked bootloaders. I really think we have enough of
them already and I'd much prefer if we started _removing_ them not
creating additional ones. The ATAG-to-DT code in the bootloader is
still rather small and it works quite well, and it allows for
configuring out ATAG support out of the kernel entirely. It should be
sufficient for all the official (e.g. upstream) ATAGs already. If
that's not good enough then people should consider the impedance matcher
approach.
> We could augment that with code to update DT too so that we can export
> just the DT based information to kexec'd kernels.
That should already be the case, no?
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 18:50 ` Nicolas Pitre
0 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-01-27 18:50 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, 27 Jan 2015, Russell King - ARM Linux wrote:
> On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> > On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > triggering old bugs. That means that this is a regression fix, and
> > > should go in ASAP).
> >
> > It is queued here:
> > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
>
> Irrespective of that patch, I commented on another thread (about adding
> the serial number to DT):
>
> | How about something a little more radical.
> |
> | Rather than trying to squeeze various ATAGs into DT, why don't we add a
> | standard ATAG to contain the DT and pass that through into the kernel.
> | This is IMHO how we _should_ have done the ATAG compatibility from the
> | start.
> |
> | That means we could get rid of most of the libfdt in the decompressor,
> | and instead resolve the differences in the kernel.
>
> That would allow us to get rid of all the FDT compatibility code in the
> decompressor, and when we encounter these special ATAGs, we can deal with
> them in the kernel instead of having to mess around with the DT. I'd
> also assume (although I haven't checked) that it would be much easier to
> add additional DT properties in the kernel environment, rather than in
> the rather restrictive decompressor environment.
Well...
I was initially against any ATAG-to-DT compatibility at all. IMHO the
"right" solution is to update the bootloader.
However people complained that updating the bootloader wasn't possible.
I therefore suggested they go with a shim layer I termed the "impedance
matcher" acting like an intermediate boot stage converting their (often
unofficial and out-of-tree) ATAGs into proper DT nodes. Some people did
exactly that and it works wonderfully for them. It also works
wonderfully for kernel maintenance as the platform specific tweaks are
kept out of the kernel tree.
Still, that wasn't good enough for some cases as the move to DT
regressed some platforms that just used to work before. Concatenating a
DTB to zImage was tolerable but installing an additional shim layer was
too much. Hence the ATAG-to-DT compat code in the decompressor. This
was meant to smooth things around the transition to DT, etc. After all,
those devices with non-replaceable bootloaders where shim layers are not
possible should get out of commission eventually?
> We'd need to be careful about how we deal with the atags vs DT. I'd
> suggest (as above) that we have a tag which points at the DT in
> physical memory, and its size, and pre-scan the atag list for that.
> When we find it, we kick off the DT based stuff as we would normally
> do, and follow it with a parse of the atags. This would cause the
> atags to override whatever is in the DT, which afaics is the behaviour
> that we actually want.
Maybe. However that would be yet another scheme for supporting legacy
platforms with locked bootloaders. I really think we have enough of
them already and I'd much prefer if we started _removing_ them not
creating additional ones. The ATAG-to-DT code in the bootloader is
still rather small and it works quite well, and it allows for
configuring out ATAG support out of the kernel entirely. It should be
sufficient for all the official (e.g. upstream) ATAGs already. If
that's not good enough then people should consider the impedance matcher
approach.
> We could augment that with code to update DT too so that we can export
> just the DT based information to kexec'd kernels.
That should already be the case, no?
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 18:50 ` Nicolas Pitre
@ 2015-01-27 23:09 ` Aaro Koskinen
-1 siblings, 0 replies; 43+ messages in thread
From: Aaro Koskinen @ 2015-01-27 23:09 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Russell King - ARM Linux, Pavel Machek, Tony Lindgren,
Pali Rohár, linux-omap, Linux Kernel Mailing List,
Sebastian Reichel, Ivaylo Dimitrov, linux-arm-kernel,
Laura Abbott
On Tue, Jan 27, 2015 at 01:50:22PM -0500, Nicolas Pitre wrote:
> Hence the ATAG-to-DT compat code in the decompressor. This
> was meant to smooth things around the transition to DT, etc. After all,
> those devices with non-replaceable bootloaders where shim layers are not
> possible should get out of commission eventually?
Probably after 5 years there are still people using and hacking mainline
Linux with N900 etc., and newer OMAPs (since there no "useful" devices)
are long forgotten...
A.
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 23:09 ` Aaro Koskinen
0 siblings, 0 replies; 43+ messages in thread
From: Aaro Koskinen @ 2015-01-27 23:09 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jan 27, 2015 at 01:50:22PM -0500, Nicolas Pitre wrote:
> Hence the ATAG-to-DT compat code in the decompressor. This
> was meant to smooth things around the transition to DT, etc. After all,
> those devices with non-replaceable bootloaders where shim layers are not
> possible should get out of commission eventually?
Probably after 5 years there are still people using and hacking mainline
Linux with N900 etc., and newer OMAPs (since there no "useful" devices)
are long forgotten...
A.
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 18:50 ` Nicolas Pitre
@ 2015-01-27 23:17 ` Pavel Machek
-1 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-27 23:17 UTC (permalink / raw)
To: Nicolas Pitre
Cc: Russell King - ARM Linux, Tony Lindgren, Pali Rohár,
linux-omap, Linux Kernel Mailing List, Aaro Koskinen,
Sebastian Reichel, Ivaylo Dimitrov, linux-arm-kernel,
Laura Abbott
On Tue 2015-01-27 13:50:22, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Russell King - ARM Linux wrote:
>
> > On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> > > On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > > triggering old bugs. That means that this is a regression fix, and
> > > > should go in ASAP).
> > >
> > > It is queued here:
> > > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
> >
> > Irrespective of that patch, I commented on another thread (about adding
> > the serial number to DT):
> >
> > | How about something a little more radical.
> > |
> > | Rather than trying to squeeze various ATAGs into DT, why don't we add a
> > | standard ATAG to contain the DT and pass that through into the kernel.
> > | This is IMHO how we _should_ have done the ATAG compatibility from the
> > | start.
> > |
> > | That means we could get rid of most of the libfdt in the decompressor,
> > | and instead resolve the differences in the kernel.
> >
> > That would allow us to get rid of all the FDT compatibility code in the
> > decompressor, and when we encounter these special ATAGs, we can deal with
> > them in the kernel instead of having to mess around with the DT. I'd
> > also assume (although I haven't checked) that it would be much easier to
> > add additional DT properties in the kernel environment, rather than in
> > the rather restrictive decompressor environment.
>
> Well...
>
> I was initially against any ATAG-to-DT compatibility at all. IMHO the
> "right" solution is to update the bootloader.
>
> However people complained that updating the bootloader wasn't possible.
> I therefore suggested they go with a shim layer I termed the "impedance
> matcher" acting like an intermediate boot stage converting their (often
> unofficial and out-of-tree) ATAGs into proper DT nodes. Some people did
> exactly that and it works wonderfully for them. It also works
> wonderfully for kernel maintenance as the platform specific tweaks are
> kept out of the kernel tree.
>
> Still, that wasn't good enough for some cases as the move to DT
> regressed some platforms that just used to work before. Concatenating a
> DTB to zImage was tolerable but installing an additional shim layer was
> too much. Hence the ATAG-to-DT compat code in the decompressor. This
> was meant to smooth things around the transition to DT, etc. After all,
> those devices with non-replaceable bootloaders where shim layers are not
> possible should get out of commission eventually?
N900 is still phone that is best-supported by the mainline,
AFAICT. Yes, it is rather sad, but it means that no, it is probably
not going out of commission anytime soon.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-01-27 23:17 ` Pavel Machek
0 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-01-27 23:17 UTC (permalink / raw)
To: linux-arm-kernel
On Tue 2015-01-27 13:50:22, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Russell King - ARM Linux wrote:
>
> > On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote:
> > > On Tue, 27 Jan 2015, Pavel Machek wrote:
> > > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > > triggering old bugs. That means that this is a regression fix, and
> > > > should go in ASAP).
> > >
> > > It is queued here:
> > > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
> >
> > Irrespective of that patch, I commented on another thread (about adding
> > the serial number to DT):
> >
> > | How about something a little more radical.
> > |
> > | Rather than trying to squeeze various ATAGs into DT, why don't we add a
> > | standard ATAG to contain the DT and pass that through into the kernel.
> > | This is IMHO how we _should_ have done the ATAG compatibility from the
> > | start.
> > |
> > | That means we could get rid of most of the libfdt in the decompressor,
> > | and instead resolve the differences in the kernel.
> >
> > That would allow us to get rid of all the FDT compatibility code in the
> > decompressor, and when we encounter these special ATAGs, we can deal with
> > them in the kernel instead of having to mess around with the DT. I'd
> > also assume (although I haven't checked) that it would be much easier to
> > add additional DT properties in the kernel environment, rather than in
> > the rather restrictive decompressor environment.
>
> Well...
>
> I was initially against any ATAG-to-DT compatibility at all. IMHO the
> "right" solution is to update the bootloader.
>
> However people complained that updating the bootloader wasn't possible.
> I therefore suggested they go with a shim layer I termed the "impedance
> matcher" acting like an intermediate boot stage converting their (often
> unofficial and out-of-tree) ATAGs into proper DT nodes. Some people did
> exactly that and it works wonderfully for them. It also works
> wonderfully for kernel maintenance as the platform specific tweaks are
> kept out of the kernel tree.
>
> Still, that wasn't good enough for some cases as the move to DT
> regressed some platforms that just used to work before. Concatenating a
> DTB to zImage was tolerable but installing an additional shim layer was
> too much. Hence the ATAG-to-DT compat code in the decompressor. This
> was meant to smooth things around the transition to DT, etc. After all,
> those devices with non-replaceable bootloaders where shim layers are not
> possible should get out of commission eventually?
N900 is still phone that is best-supported by the mainline,
AFAICT. Yes, it is rather sad, but it means that no, it is probably
not going out of commission anytime soon.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-01-27 15:16 ` Nicolas Pitre
@ 2015-02-02 13:39 ` Pavel Machek
-1 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-02-02 13:39 UTC (permalink / raw)
To: Nicolas Pitre, Linus Torvalds
Cc: Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott,
Russell King
On Tue 2015-01-27 10:16:24, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> >
> > > > > I would say, problem is because omap3-n900 binary DT is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to me. It also
> > > > seems we can have the temporary stack be larger than the initial
> > > > stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location. We need to
> > > position it away from the DT data. The DT size is known and we could
> > > use that, plus some room for the insertion of new data coming from the
> > > ATAG conversion.
> > >
> > > Something like the following would be a more robust solution:
> >
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Hmm, but it should be on kernel.org, not in private arm trees, as it
fixes a regression. Russell, you are the ARM maintainer, can you push
it to Linus?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-02-02 13:39 ` Pavel Machek
0 siblings, 0 replies; 43+ messages in thread
From: Pavel Machek @ 2015-02-02 13:39 UTC (permalink / raw)
To: linux-arm-kernel
On Tue 2015-01-27 10:16:24, Nicolas Pitre wrote:
> On Tue, 27 Jan 2015, Pavel Machek wrote:
>
> >
> > > > > I would say, problem is because omap3-n900 binary DT is too large
> > >
> > > I agree.
> > >
> > > > OK if that's the case, then your patch makes sense to me. It also
> > > > seems we can have the temporary stack be larger than the initial
> > > > stack just for atags_to_fdt.
> > >
> > > The stack size isn't the issue, but rather its location. We need to
> > > position it away from the DT data. The DT size is known and we could
> > > use that, plus some room for the insertion of new data coming from the
> > > ATAG conversion.
> > >
> > > Something like the following would be a more robust solution:
> >
> > Tested-by: Pavel Machek <pavel@ucw.cz>
> >
> > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > triggering old bugs. That means that this is a regression fix, and
> > should go in ASAP).
>
> It is queued here:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
Hmm, but it should be on kernel.org, not in private arm trees, as it
fixes a regression. Russell, you are the ARM maintainer, can you push
it to Linus?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: N900 v3.19-rc5 arm atags_to_fdt.c is broken
2015-02-02 13:39 ` Pavel Machek
@ 2015-02-02 13:56 ` Nicolas Pitre
-1 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-02-02 13:56 UTC (permalink / raw)
To: Pavel Machek
Cc: Linus Torvalds, Tony Lindgren, Pali Rohár, linux-omap,
Linux Kernel Mailing List, Aaro Koskinen, Sebastian Reichel,
Ivaylo Dimitrov, Russell King, linux-arm-kernel, Laura Abbott,
Russell King
On Mon, 2 Feb 2015, Pavel Machek wrote:
> On Tue 2015-01-27 10:16:24, Nicolas Pitre wrote:
> > On Tue, 27 Jan 2015, Pavel Machek wrote:
> >
> > >
> > > > > > I would say, problem is because omap3-n900 binary DT is too large
> > > >
> > > > I agree.
> > > >
> > > > > OK if that's the case, then your patch makes sense to me. It also
> > > > > seems we can have the temporary stack be larger than the initial
> > > > > stack just for atags_to_fdt.
> > > >
> > > > The stack size isn't the issue, but rather its location. We need to
> > > > position it away from the DT data. The DT size is known and we could
> > > > use that, plus some room for the insertion of new data coming from the
> > > > ATAG conversion.
> > > >
> > > > Something like the following would be a more robust solution:
> > >
> > > Tested-by: Pavel Machek <pavel@ucw.cz>
> > >
> > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > triggering old bugs. That means that this is a regression fix, and
> > > should go in ASAP).
> >
> > It is queued here:
> > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
>
> Hmm, but it should be on kernel.org, not in private arm trees, as it
> fixes a regression. Russell, you are the ARM maintainer, can you push
> it to Linus?
The patch is included in RMK's "fixes" branch already, along with other
fixes. I suppose it'll make its way to Linus before v3.19 final.
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread
* N900 v3.19-rc5 arm atags_to_fdt.c is broken
@ 2015-02-02 13:56 ` Nicolas Pitre
0 siblings, 0 replies; 43+ messages in thread
From: Nicolas Pitre @ 2015-02-02 13:56 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, 2 Feb 2015, Pavel Machek wrote:
> On Tue 2015-01-27 10:16:24, Nicolas Pitre wrote:
> > On Tue, 27 Jan 2015, Pavel Machek wrote:
> >
> > >
> > > > > > I would say, problem is because omap3-n900 binary DT is too large
> > > >
> > > > I agree.
> > > >
> > > > > OK if that's the case, then your patch makes sense to me. It also
> > > > > seems we can have the temporary stack be larger than the initial
> > > > > stack just for atags_to_fdt.
> > > >
> > > > The stack size isn't the issue, but rather its location. We need to
> > > > position it away from the DT data. The DT size is known and we could
> > > > use that, plus some room for the insertion of new data coming from the
> > > > ATAG conversion.
> > > >
> > > > Something like the following would be a more robust solution:
> > >
> > > Tested-by: Pavel Machek <pavel@ucw.cz>
> > >
> > > (Note, that in 3.19 dts for n900 got too big, so we are actually
> > > triggering old bugs. That means that this is a regression fix, and
> > > should go in ASAP).
> >
> > It is queued here:
> > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1
>
> Hmm, but it should be on kernel.org, not in private arm trees, as it
> fixes a regression. Russell, you are the ARM maintainer, can you push
> it to Linus?
The patch is included in RMK's "fixes" branch already, along with other
fixes. I suppose it'll make its way to Linus before v3.19 final.
Nicolas
^ permalink raw reply [flat|nested] 43+ messages in thread