omap3evm: Pass 'mem' argument to linux kernel
PATCH 1/1 omap3evm: Pass 'mem' argument to linux kernel
In absence of this argument, Linux kernel doesn't boot.
Default value has been set to 128M to ensure that
Linux kernel boots on older EVMs as well.
---
This patch has been created against u-boot-ti/next.
include/configs/omap3_evm.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
include/configs/omap3_evm.h +3 -0
@@ -200,11 +200,14 @@"loadaddr=0x82000000\0" \"usbtty=cdc_acm\0" \"mmcdev=0\0" \ +"memsize=128M\0" \"console=ttyO0,115200n8\0" \"mmcargs=setenv bootargs console=${console} " \ +"mem=${memsize}\0 " \"root=/dev/mmcblk0p2 rw " \"rootfstype=ext3 rootwait\0" \"nandargs=setenv bootargs console=${console} " \ +"mem=${memsize}\0 " \"root=/dev/mtdblock4 rw " \"rootfstype=jffs2\0" \"loadbootscript=fatload mmc ${mmcdev} ${loadaddr} boot.scr\0" \
Signature · 1 line
1.7.0.4
PATCH 1/1 omap3evm: Pass 'mem' argument to linux kernel
Quoted 4 lines · Sanjeev Premi
In absence of this argument, Linux kernel doesn't boot.
Default value has been set to 128M to ensure that
Linux kernel boots on older EVMs as well.
This change affects all EVMs, unless they explicitly change/remove the memsize variable or change the *args variables.
Can't the get_ram_size() function be used for detecting the actual amount of RAM? and then the memory tag or FDT equivalent (if there is one) used to pass the memory size information?
Quoted 29 lines
Signed-off-by Sanjeev Premi <[email protected]>Cc Sandeep Paulraj <[email protected]>---
This patch has been created against u-boot-ti/next.
include/configs/omap3_evm.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)include/configs/omap3_evm.h +3
-0@@ -200,11 +200,14 @@"loadaddr=0x82000000\0" \"usbtty=cdc_acm\0" \"mmcdev=0\0" \ +"memsize=128M\0" \"console=ttyO0,115200n8\0" \"mmcargs=setenv bootargs console=${console} " \ +"mem=${memsize}\0 " \"root=/dev/mmcblk0p2 rw " \"rootfstype=ext3 rootwait\0" \"nandargs=setenv bootargs console=${console} " \ +"mem=${memsize}\0 " \"root=/dev/mtdblock4 rw " \"rootfstype=jffs2\0" \"loadbootscript=fatload mmc ${mmcdev} ${loadaddr} boot.scr\0" \
Signature · 2 lines
Regards, Igor.
Premi
PATCH 1/1 omap3evm: Pass 'mem' argument to linux kernel
Quoted 7 lines
-----Original Message-----
From: Igor Grinberg [mailto:grinberg at compulab.co.il]
Sent: Tuesday, September 27, 2011 5:35 PM
To: Premi, Sanjeev
Cc: u-boot at lists.denx.de
Subject: Re: [U-Boot] [PATCH] omap3evm: Pass 'mem' argument to linux kernel
Sorry missed this mail earlier...
Quoted 9 lines · Sanjeev Premi
Quoted 4 lines
In absence of this argument, Linux kernel doesn't boot.
Default value has been set to 128M to ensure that
Linux kernel boots on older EVMs as well.This change affects all EVMs, unless they explicitly change/remove the memsize variable or change the *args variables.
Today without this patch, all EVMs should anyway be broken :( ...but may be working as users may have their own bootargs with "mem=XYZM" in their bootargs.
The patch only ensures that the kernel would boot if there was no "saved" environment e.g. when environment partition is erased. or when u-boot is flashed on new boards.
Quoted 5 lines
Can't the
get_ram_size()function be used for detecting the actual amount of RAM? and then the memory tag or FDT equivalent (if there is one) used to pass the memory size information?
Yes something like this can be done, but that would mean string manipulation at run-time. Question is - when we should/ shouldn't do this manipulation.
If user wants to explicitly pass only a portion of memory to Linux using environment variables, we shouldn't be manipulating the bootargs.
~sanjeev
[snip]...[snip]
PATCH 1/1 omap3evm: Pass 'mem' argument to linux kernel
Dear "Premi, Sanjeev",
Quoted 8 lines · In message <[email protected]> you…
Quoted 4 lines
Can't the
get_ram_size()function be used for detecting the actual amount of RAM? and then the memory tag or FDT equivalent (if there is one) used to pass the memory size information?Yes something like this can be done, but that would mean string manipulation at run-time. Question is - when we should/ shouldn't do this manipulation.
I don't understand what you are trying to say.
There are two possibilities:
- In a FDT enabled kernel, memory information is passed in the device tree; no "string manipulation" is needed anywhere. If the user decides to overwrite the auto-detected settings by using a "mem=" boot argument, this is his decision and of course he can do so.
- Without FDT support, on ARM systems we pass a memory information in one or more ATAG_MEM entries. Again, no "string manipulation" is needed anywhere.
Quoted 3 lines
If user wants to explicitly pass only a portion of memory to Linux using environment variables, we shouldn't be manipulating the bootargs.
This statement makes even less ense to me. Passing a "mem=" boot argument is the official, documented way to acchive this. So what makes you think we should not pass such a boot argument?
Best regards,
Wolfgang Denk
Signature · 7 lines
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
How many seconds are there in a year? If I tell you there are 3.155 x
10^7, you won't even try to remember it. On the other hand, who could
forget that, to within half a percent, pi seconds is a nanocentury.
- Tom Duff, Bell LabsPATCH 1/1 omap3evm: Pass 'mem' argument to linux kernel
In reply to Sanjeev PremiDear Sanjeev Premi,
Quoted 8 lines · In message <[email protected]> you wrote:
In absence of this argument, Linux kernel doesn't boot.
Default value has been set to 128M to ensure that
Linux kernel boots on older EVMs as well.Signed-off-by Sanjeev Premi <[email protected]>Cc Sandeep Paulraj <[email protected]>---
Why do we need to pass any mem= argument at all? This should never be necessary. If it is, then this is a bug in the Linux kernel and needs to be fixed there.
Best regards,
Wolfgang Denk
Signature · 7 lines
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de "I think they're going to take all this money that we spend now on war and death --" "And make them spend it on life." -- Edith Keeler and Kirk, "The City on the Edge of Forever", stardate unknown.