Why eeprom driver is read-only ?

Why eeprom driver is read-only ?

[Ranran]

Hello,

What is the reason that kernel driver of eeprom is configured only as
read-only ?

Is it because the BIOS is stored there ?

Is there a way to make it writable ?

Thank you,
Ran

Why eeprom driver is read-only ?

[Ranran]

Hello,

What is the reason that kernel driver of eeprom is configured only as
read-only ?

Is it because the BIOS is stored there ?

Is there a way to make it writable ?

Thank you,
Ran

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Why eeprom driver is read-only ?

[Ruben Safir]

On 11/19/18 7:08 AM, Ranran wrote:
> Hello,
> 
> What is the reason that kernel driver of eeprom is configured only as
> read-only ?
> 
> Is it because the BIOS is stored there ?
> 
> Is there a way to make it writable ?
> 
> Thank you,
> Ran
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> 


because the ROM is read only?


-- 
So many immigrant groups have swept through our town
that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

http://www.nylxs.com - Leadership Development in Free Software
http://www.brooklyn-living.com

Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013

Re: Why eeprom driver is read-only ?

[Ruben Safir]

On 11/19/18 7:08 AM, Ranran wrote:
> Hello,
> 
> What is the reason that kernel driver of eeprom is configured only as
> read-only ?
> 
> Is it because the BIOS is stored there ?
> 
> Is there a way to make it writable ?
> 
> Thank you,
> Ran
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> 


because the ROM is read only?


-- 
So many immigrant groups have swept through our town
that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

http://www.nylxs.com - Leadership Development in Free Software
http://www.brooklyn-living.com

Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013

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Why eeprom driver is read-only ?

[Chriz Chow]

Hello,

It seems that some drivers in drivers/misc/eeprom does support write access. For example at24.c seems to have a function at24_write().

https://github.com/torvalds/linux/blob/master/drivers/misc/eeprom/at24.c

However some drivers doesn?t have write support, I believe it is because of simplicity - some eeprom are used for read only, such as ddr4 spd eeprom.

Point me out if I am wrong. 

Chriz

Enviado desde mi iPhone

> El 19 nov 2018, a las 9:12 p. m., Ruben Safir <ruben@mrbrklyn.com> escribi?:
> 
>> On 11/19/18 7:08 AM, Ranran wrote:
>> Hello,
>> 
>> What is the reason that kernel driver of eeprom is configured only as
>> read-only ?
>> 
>> Is it because the BIOS is stored there ?
>> 
>> Is there a way to make it writable ?
>> 
>> Thank you,
>> Ran
>> 
>> _______________________________________________
>> Kernelnewbies mailing list
>> Kernelnewbies at kernelnewbies.org
>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>> 
> 
> 
> because the ROM is read only?
> 
> 
> -- 
> So many immigrant groups have swept through our town
> that Brooklyn, like Atlantis, reaches mythological
> proportions in the mind of the world - RI Safir 1998
> http://www.mrbrklyn.com
> DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
> 
> http://www.nylxs.com - Leadership Development in Free Software
> http://www.brooklyn-living.com
> 
> Being so tracked is for FARM ANIMALS and and extermination camps,
> but incompatible with living as a free human being. -RI Safir 2013
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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Re: Why eeprom driver is read-only ?

[Chriz Chow]

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Hello,

It seems that some drivers in drivers/misc/eeprom does support write access. For example at24.c seems to have a function at24_write().

https://github.com/torvalds/linux/blob/master/drivers/misc/eeprom/at24.c

However some drivers doesn’t have write support, I believe it is because of simplicity - some eeprom are used for read only, such as ddr4 spd eeprom.

Point me out if I am wrong. 

Chriz

Enviado desde mi iPhone

> El 19 nov 2018, a las 9:12 p. m., Ruben Safir <ruben@mrbrklyn.com> escribió:
> 
>> On 11/19/18 7:08 AM, Ranran wrote:
>> Hello,
>> 
>> What is the reason that kernel driver of eeprom is configured only as
>> read-only ?
>> 
>> Is it because the BIOS is stored there ?
>> 
>> Is there a way to make it writable ?
>> 
>> Thank you,
>> Ran
>> 
>> _______________________________________________
>> Kernelnewbies mailing list
>> Kernelnewbies@kernelnewbies.org
>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>> 
> 
> 
> because the ROM is read only?
> 
> 
> -- 
> So many immigrant groups have swept through our town
> that Brooklyn, like Atlantis, reaches mythological
> proportions in the mind of the world - RI Safir 1998
> http://www.mrbrklyn.com
> DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
> 
> http://www.nylxs.com - Leadership Development in Free Software
> http://www.brooklyn-living.com
> 
> Being so tracked is for FARM ANIMALS and and extermination camps,
> but incompatible with living as a free human being. -RI Safir 2013
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

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Why eeprom driver is read-only ?

[valdis.kletnieks at vt.edu]

On Mon, 19 Nov 2018 14:08:26 +0200, Ranran said:

> What is the reason that kernel driver of eeprom is configured only as
> read-only ?

Probably depends on the hardware.  I'm pretty sure that *some* eeproms
are writable.

> Is it because the BIOS is stored there ?

Remember that the BIOS is stored in one of what may be several eeproms in the
system - graphics cards and other controllers probably have their own eeproms.

You might want to think about why most systems do a restart after updating the BIOS,
and then ask yourself if you really want to write to it while the system is up....

> Is there a way to make it writable ?

Depends on which eeprom you're talking about.
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Re: Why eeprom driver is read-only ?

[valdis.kletnieks]

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On Mon, 19 Nov 2018 14:08:26 +0200, Ranran said:

> What is the reason that kernel driver of eeprom is configured only as
> read-only ?

Probably depends on the hardware.  I'm pretty sure that *some* eeproms
are writable.

> Is it because the BIOS is stored there ?

Remember that the BIOS is stored in one of what may be several eeproms in the
system - graphics cards and other controllers probably have their own eeproms.

You might want to think about why most systems do a restart after updating the BIOS,
and then ask yourself if you really want to write to it while the system is up....

> Is there a way to make it writable ?

Depends on which eeprom you're talking about.

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Why eeprom driver is read-only ?

[Ranran]

On Mon, Nov 19, 2018 at 3:13 PM Ruben Safir <ruben@mrbrklyn.com> wrote:
>
> On 11/19/18 7:08 AM, Ranran wrote:
> > Hello,
> >
> > What is the reason that kernel driver of eeprom is configured only as
> > read-only ?
> >
> > Is it because the BIOS is stored there ?
> >
> > Is there a way to make it writable ?
> >
> > Thank you,
> > Ran
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
>
>
> because the ROM is read only?
>

That's interesting...
I think the name is confusing, because this chips are also writable.

Not only this, but in arm the eeprom (at24) is writable!
But in the x86 I am using, it is readonly in kernel code:
https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
static struct bin_attribute eeprom_attr = {
.attr = {
.name = "eeprom",
.mode = S_IRUGO,
},
.size = EEPROM_SIZE,
.read = eeprom_read,
};

Regards,
ran



>
> --
> So many immigrant groups have swept through our town
> that Brooklyn, like Atlantis, reaches mythological
> proportions in the mind of the world - RI Safir 1998
> http://www.mrbrklyn.com
> DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
>
> http://www.nylxs.com - Leadership Development in Free Software
> http://www.brooklyn-living.com
>
> Being so tracked is for FARM ANIMALS and and extermination camps,
> but incompatible with living as a free human being. -RI Safir 2013
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Why eeprom driver is read-only ?

[Ranran]

On Mon, Nov 19, 2018 at 3:13 PM Ruben Safir <ruben@mrbrklyn.com> wrote:
>
> On 11/19/18 7:08 AM, Ranran wrote:
> > Hello,
> >
> > What is the reason that kernel driver of eeprom is configured only as
> > read-only ?
> >
> > Is it because the BIOS is stored there ?
> >
> > Is there a way to make it writable ?
> >
> > Thank you,
> > Ran
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies@kernelnewbies.org
> > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
>
>
> because the ROM is read only?
>

That's interesting...
I think the name is confusing, because this chips are also writable.

Not only this, but in arm the eeprom (at24) is writable!
But in the x86 I am using, it is readonly in kernel code:
https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
static struct bin_attribute eeprom_attr = {
.attr = {
.name = "eeprom",
.mode = S_IRUGO,
},
.size = EEPROM_SIZE,
.read = eeprom_read,
};

Regards,
ran



>
> --
> So many immigrant groups have swept through our town
> that Brooklyn, like Atlantis, reaches mythological
> proportions in the mind of the world - RI Safir 1998
> http://www.mrbrklyn.com
> DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
>
> http://www.nylxs.com - Leadership Development in Free Software
> http://www.brooklyn-living.com
>
> Being so tracked is for FARM ANIMALS and and extermination camps,
> but incompatible with living as a free human being. -RI Safir 2013
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

_______________________________________________
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Why eeprom driver is read-only ?

[valdis.kletnieks at vt.edu]

On Tue, 20 Nov 2018 00:04:03 +0200, Ranran said:

> That's interesting...
> I think the name is confusing, because this chips are also writable.
>
> Not only this, but in arm the eeprom (at24) is writable!
> But in the x86 I am using, it is readonly in kernel code:
> https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
> static struct bin_attribute eeprom_attr = {
> .attr = {
> .name = "eeprom",
> .mode = S_IRUGO,
> },
> .size = EEPROM_SIZE,
> .read = eeprom_read,
> };

Well, at least in the mainline kernel, we have this at the top of the eeprom.c file:

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
                                        0x55, 0x56, 0x57, I2C_CLIENT_END };


/* Size of EEPROM in bytes */
#define EEPROM_SIZE             256

which is pretty obviously intended for "very small eeprom hanging off an I2C adapter",
and thus probably *NOT* the boot ROM that the BIOS lives in.
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Re: Why eeprom driver is read-only ?

[valdis.kletnieks]

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On Tue, 20 Nov 2018 00:04:03 +0200, Ranran said:

> That's interesting...
> I think the name is confusing, because this chips are also writable.
>
> Not only this, but in arm the eeprom (at24) is writable!
> But in the x86 I am using, it is readonly in kernel code:
> https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
> static struct bin_attribute eeprom_attr = {
> .attr = {
> .name = "eeprom",
> .mode = S_IRUGO,
> },
> .size = EEPROM_SIZE,
> .read = eeprom_read,
> };

Well, at least in the mainline kernel, we have this at the top of the eeprom.c file:

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
                                        0x55, 0x56, 0x57, I2C_CLIENT_END };


/* Size of EEPROM in bytes */
#define EEPROM_SIZE             256

which is pretty obviously intended for "very small eeprom hanging off an I2C adapter",
and thus probably *NOT* the boot ROM that the BIOS lives in.

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Why eeprom driver is read-only ?

[Ranran]

On Tue, Nov 20, 2018 at 12:32 AM <valdis.kletnieks@vt.edu> wrote:
>
> On Tue, 20 Nov 2018 00:04:03 +0200, Ranran said:
>
> > That's interesting...
> > I think the name is confusing, because this chips are also writable.
> >
> > Not only this, but in arm the eeprom (at24) is writable!
> > But in the x86 I am using, it is readonly in kernel code:
> > https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
> > static struct bin_attribute eeprom_attr = {
> > .attr = {
> > .name = "eeprom",
> > .mode = S_IRUGO,
> > },
> > .size = EEPROM_SIZE,
> > .read = eeprom_read,
> > };
>
> Well, at least in the mainline kernel, we have this at the top of the eeprom.c file:
>
> /* Addresses to scan */
> static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
>                                         0x55, 0x56, 0x57, I2C_CLIENT_END };
>
>
> /* Size of EEPROM in bytes */
> #define EEPROM_SIZE             256
>
> which is pretty obviously intended for "very small eeprom hanging off an I2C adapter",
> and thus probably *NOT* the boot ROM that the BIOS lives in.

although I think that in my system it is a flash rom which stores the
BIOS, so I really don't know what's the use of the eeprom....

I need a very small amout of data (several bytes) to save some non
volatile information in x86 system.
I can't use disk for this, but can use any other peripheral or even
x86 chip on board.
Now it also seems that I can't use the eeprom becuase of the kernel
limitation (can I open it for writing if the BIOS is not stored
there??)

I don't have any idea where I can find such storage.
Does x86 include some programmable registers ?
Do you have any idea where I can store the data ?

Thanks

Re: Why eeprom driver is read-only ?

[Ranran]

On Tue, Nov 20, 2018 at 12:32 AM <valdis.kletnieks@vt.edu> wrote:
>
> On Tue, 20 Nov 2018 00:04:03 +0200, Ranran said:
>
> > That's interesting...
> > I think the name is confusing, because this chips are also writable.
> >
> > Not only this, but in arm the eeprom (at24) is writable!
> > But in the x86 I am using, it is readonly in kernel code:
> > https://android.googlesource.com/kernel/omap/+/glass-omap-xrr02/drivers/misc/eeprom/eeprom.c
> > static struct bin_attribute eeprom_attr = {
> > .attr = {
> > .name = "eeprom",
> > .mode = S_IRUGO,
> > },
> > .size = EEPROM_SIZE,
> > .read = eeprom_read,
> > };
>
> Well, at least in the mainline kernel, we have this at the top of the eeprom.c file:
>
> /* Addresses to scan */
> static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
>                                         0x55, 0x56, 0x57, I2C_CLIENT_END };
>
>
> /* Size of EEPROM in bytes */
> #define EEPROM_SIZE             256
>
> which is pretty obviously intended for "very small eeprom hanging off an I2C adapter",
> and thus probably *NOT* the boot ROM that the BIOS lives in.

although I think that in my system it is a flash rom which stores the
BIOS, so I really don't know what's the use of the eeprom....

I need a very small amout of data (several bytes) to save some non
volatile information in x86 system.
I can't use disk for this, but can use any other peripheral or even
x86 chip on board.
Now it also seems that I can't use the eeprom becuase of the kernel
limitation (can I open it for writing if the BIOS is not stored
there??)

I don't have any idea where I can find such storage.
Does x86 include some programmable registers ?
Do you have any idea where I can store the data ?

Thanks

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