Re: [uml-devel] Emulate I2C subsystem/slaves

[Richard Weinberger]

Am 09.09.2012 14:15, schrieb Peter Hüwe:
 Am Sonntag, 9. September 2012, 13:28:38 schrieb Jean Delvare:
 Thanks for the info. I thought UML was no longer used with all the
 virtualization solutions available, but apparently I was wrong.
 I guess it's mainly used for sandboxing, testing and development ;)

It's mostly used where KVM does not work.
For example low end i586 servers in schools.
Using UML you can still run 10+ instances on a P3 with 512MiB ram.

 
 My bet is that all I2C bus drivers do use I/O or memory mapped
 operations directly or indirectly, except i2c-stub. So it would
 probably make more sense, and be a less intrusive change, to move the
 HAS_IOMEM dependency to drivers/i2c/busses, and move (logically or for
 real) i2c-stub out of it.

 Or are there really other I2C bus drivers which make sense to enable
 under UML?
 The only other available in UML which doesn't rely on HAS_IOMEM is the 
 PARPORT_LIGHT which relies on direct io access - so I guess this one doesn't 
 make sense either.
 
 I created a patch for your proposed solution, I moved the stub driver to the 
 end in order to have only one big if HAS_IOMEM.

UML does not have IO_MEM but some sub-systems have depend HAS_IOMEM which is
often too coarse grained.
To deal with that I've introduced GENERIC_IO some time ago to support MTD (and 
nandsim)
on UML.
Maybe some parts of the I2C sub-system can also just depend on GENERIC_IO 
instead of
HAS_IOMEM.
An arch has GENERIC_IO=y if it supports everything defined in generic-asm/io.h 
which is
more than enough for most stub drivers.

Please look at this patch series:
https://lkml.org/lkml/2012/2/6/489

I'm sure it will help you in bringing I2C to UML.

Thanks,
//richard



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Re: [uml-devel] Emulate I2C subsystem/slaves

[Jean Delvare]

Hi all,

Thanks for the info. I thought UML was no longer used with all the
virtualization solutions available, but apparently I was wrong.

On Sun, 9 Sep 2012 12:49:03 +0200, Peter Hüwe wrote:
  That's because they rely on the HAS_IOMEM dependency for the whole
  subsystem. In fact, I'm surprised you didn't have to add HAS_IOMEM
  dependencies to more drivers.
 I changed only the ones which are available in UML.
 I now rewrote the patch to remove the global dependency and move it to all 
 the 
 drivers that really rely on HAS_IOMEM - see below.

My bet is that all I2C bus drivers do use I/O or memory mapped
operations directly or indirectly, except i2c-stub. So it would
probably make more sense, and be a less intrusive change, to move the
HAS_IOMEM dependency to drivers/i2c/busses, and move (logically or for
real) i2c-stub out of it.

Or are there really other I2C bus drivers which make sense to enable
under UML?

Are there other subsystems where the HAS_IOMEM dependency is at the
individual driver level?

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Re: [uml-devel] Emulate I2C subsystem/slaves

[Peter Hüwe]

Am Sonntag, 9. September 2012, 14:23:06 schrieb Richard Weinberger: 
 UML does not have IO_MEM but some sub-systems have depend HAS_IOMEM which
 is often too coarse grained.
 To deal with that I've introduced GENERIC_IO some time ago to support MTD
 (and nandsim) on UML.
 Maybe some parts of the I2C sub-system can also just depend on GENERIC_IO
 instead of HAS_IOMEM.
 An arch has GENERIC_IO=y if it supports everything defined in
 generic-asm/io.h which is more than enough for most stub drivers.

The only thing which seems to be missing on UML is the ioremap function family 
;/


Peter


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Re: [uml-devel] Emulate I2C subsystem/slaves

[Peter Hüwe]

  Maybe some parts of the I2C sub-system can also just depend on
  GENERIC_IO instead of HAS_IOMEM.
  An arch has GENERIC_IO=y if it supports everything defined in
  generic-asm/io.h which is more than enough for most stub drivers.
  
  The only thing which seems to be missing on UML is the ioremap function
  family ;/
 
 Why do you need ioremap() in a stub driver?
 This sounds strange.


This was a misunderstanding - the main part of the I2C subsystem doesn't 
depend at all on HAS_IOMEM, only the main part of the i2c/busses section.
And almost all of those drivers use ioremap.

For my stub driver I don't need any of that, I'd be fine with the move of 
HAS_IOMEM as proposed by Jean.


Peter

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Re: [uml-devel] Emulate I2C subsystem/slaves

[Richard Weinberger]

Am 09.09.2012 15:11, schrieb Peter Hüwe:
 Maybe some parts of the I2C sub-system can also just depend on
 GENERIC_IO instead of HAS_IOMEM.
 An arch has GENERIC_IO=y if it supports everything defined in
 generic-asm/io.h which is more than enough for most stub drivers.

 The only thing which seems to be missing on UML is the ioremap function
 family ;/

 Why do you need ioremap() in a stub driver?
 This sounds strange.
 
 
 This was a misunderstanding - the main part of the I2C subsystem doesn't 
 depend at all on HAS_IOMEM, only the main part of the i2c/busses section.
 And almost all of those drivers use ioremap.

Sure. They need real hardware. :-)

 For my stub driver I don't need any of that, I'd be fine with the move of 
 HAS_IOMEM as proposed by Jean.

IMHO you should replace the HAS_IOMEM with GENERIC_IO.
Otherwise you may break the build on s390.

Thanks,
//richard



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Re: [uml-devel] Emulate I2C subsystem/slaves

[Geert Uytterhoeven]

On Sun, Sep 9, 2012 at 3:27 PM, Richard Weinberger rich...@nod.at wrote:
 For my stub driver I don't need any of that, I'd be fine with the move of
 HAS_IOMEM as proposed by Jean.

 IMHO you should replace the HAS_IOMEM with GENERIC_IO.
 Otherwise you may break the build on s390.

s390 has neither of HAS_IOMEM and GENERIC_IO, so it won't break their
build.

Gr{oetje,eeting}s,

Geert

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Re: [uml-devel] Emulate I2C subsystem/slaves

[Richard Weinberger]

Geert Uytterhoeven ge...@linux-m68k.org schrieb:

On Sun, Sep 9, 2012 at 3:27 PM, Richard Weinberger rich...@nod.at
wrote:
 For my stub driver I don't need any of that, I'd be fine with the
move of
 HAS_IOMEM as proposed by Jean.

 IMHO you should replace the HAS_IOMEM with GENERIC_IO.
 Otherwise you may break the build on s390.

s390 has neither of HAS_IOMEM and GENERIC_IO, so it won't break their
build.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
ge...@linux-m68k.org

In personal conversations with technical people, I call myself a
hacker. But
when I'm talking to journalists I just say programmer or something
like that.
-- Linus Torvalds

That's why it may break. If you remove the depends on HAS_IOMEM, it will be 
built on s390 and fail if that codes uses io memory functions. Depending on 
GENERIC_IO fixes that.

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Re: [uml-devel] [PATCH/RFC] um: Preinclude include/linux/kern_levels.h

[Joe Perches]

On Sun, 2012-09-09 at 10:33 +0200, Geert Uytterhoeven wrote:
 Ping?

Richard?  Are you going to pick up this patch?
It seems sensible.

Geert, I suggest sending it directly to Linus as a fix
if Richard doesn't respond in a few days.

 On Thu, Aug 16, 2012 at 8:15 PM, Geert Uytterhoeven
 ge...@linux-m68k.org wrote:
  The userspace part of UML uses the asm-offsets.h generator mechanism to
  create definitions for UM_KERN_LEVEL that match the in-kernel
  KERN_LEVEL constant definitions.
 
  As of commit 04d2c8c83d0e3ac5f78aeede51babb3236200112 (printk: convert
  the format for KERN_LEVEL to a 2 byte pattern), KERN_LEVEL is no
  longer expanded to the literal 'LEVEL', but to '\001 LEVEL', i.e.
  it contains two parts.
 
  However, the combo of DEFINE_STR() in
  arch/x86/um/shared/sysdep/kernel-offsets.h and sed-y in Kbuild doesn't
  support string literals consisting of multiple parts. Hence for all
  UM_KERN_LEVEL definitions, only the SOH character is retained in the 
  actual
  definition, while the remainder ends up in the comment. E.g. in
  include/generated/asm-offsets.h we get
 
  #define UM_KERN_INFO \001 /* 6 KERN_INFO */
 
  instead of
 
  #define UM_KERN_INFO \001 6 /* KERN_INFO */
 
  This causes spurious '^A' output in some kernel messages:



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Re: [uml-devel] Emulate I2C subsystem/slaves

[Jean Delvare]

On Sun, 09 Sep 2012 17:00:54 +0200, Richard Weinberger wrote:
 Geert Uytterhoeven ge...@linux-m68k.org schrieb:
 s390 has neither of HAS_IOMEM and GENERIC_IO, so it won't break their
 build.

 That's why it may break. If you remove the depends on HAS_IOMEM, it will be 
 built on s390 and fail if that codes uses io memory functions. Depending on 
 GENERIC_IO fixes that.

Where that is a problem which may not exist in the first place.

-- 
Jean Delvare

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Re: [uml-devel] [PATCH/RFC] um: Preinclude include/linux/kern_levels.h

[Richard Weinberger]

Am 09.09.2012 17:09, schrieb Joe Perches:
 On Sun, 2012-09-09 at 10:33 +0200, Geert Uytterhoeven wrote:
 Ping?
 
 Richard?  Are you going to pick up this patch?
 It seems sensible.
 
 Geert, I suggest sending it directly to Linus as a fix
 if Richard doesn't respond in a few days.

I'll pick up.
I'm still on vacation and therefore a bit slow. :)

Thanks,
//richard



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Re: [uml-devel] Emulate I2C subsystem/slaves

[Peter Hüwe]

 That's why it may break. If you remove the depends on HAS_IOMEM, it will be
 built on s390 and fail if that codes uses io memory functions. Depending
 on GENERIC_IO fixes that.

Everything I can select in I2C subsystem compiles fine on s390.
(using defconfig + menuconfig).
Just compiled it.

Thanks,
Peter


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