Background:
We have recently upgraded our board (similar to the P2020RDB) to use a 256MB NOR flash, up from 64MB NOR. During boot, the kernel complains about not being able to vmalloc enough space to cover the increased 256MB NOR:
Memory: 2005736K/2097152K available (5828K kernel code, 304K rwdata, 1604K rodata, 248K init, 183K bss, 91416K reserved, 1310716K highmem)
Kernel virtual memory layout:
* 0xfffbf000..0xfffff000 : fixmap
* 0xff800000..0xffc00000 : highmem PTEs
* 0xff7fc000..0xff800000 : early ioremap
* 0xf1000000..0xff7fc000 : vmalloc & ioremap
...
vmap allocation for size 268439552 failed: use vmalloc=<size> to increase size.
of-flash e0000000.nor: Failed to ioremap() flash region
of-flash: probe of e0000000.nor failed with error -12
Based on this forum thread:
How can I get more vmalloc/ioremap space?
We previously (LTIB-era) shifted the page_offset / task_size boundary to allow for more kernel and vmalloc space with the following kernel-config subsection:
#
# Advanced setup
#
CONFIG_ADVANCED_OPTIONS=y
CONFIG_LOWMEM_SIZE_BOOL=y
CONFIG_LOWMEM_SIZE=0x30000000
# CONFIG_LOWMEM_CAM_NUM_BOOL is not set
CONFIG_LOWMEM_CAM_NUM=3
# CONFIG_RELOCATABLE is not set
CONFIG_PAGE_OFFSET_BOOL=y
CONFIG_PAGE_OFFSET=0xa0000000
CONFIG_KERNEL_START_BOOL=y
CONFIG_KERNEL_START=0xa0000000
# CONFIG_PHYSICAL_START_BOOL is not set
CONFIG_PHYSICAL_START=0x00000000
CONFIG_PHYSICAL_ALIGN=0x04000000
CONFIG_TASK_SIZE_BOOL=y
CONFIG_TASK_SIZE=0xa0000000
CONFIG_NET=y
We recently updated to the latest SDK 1.7, which also exhibits the same VMALLOC era. So, after a full Yocto/SDK-1.7 build for the P2020RDB, I have tried to modify the kernel config with the above options by following these directions:
Linux Kernel
Which are in short:
$ cd <SDK-V1.7>/poky/build_p2020rdb_release
$ bitbake -c menuconfig virtual/kernel
<... make above changes via Advanced menu ...>
$ bitbake -c compile -f virtual/kernel
$ bitbake virtual/kernel
$ cp -L tmp/deploy/images/p2020rdb/uImage <TFTP server path to test new kernel>
Problem:
Here's the problem: Many of my changes persist and are included in the new kernel. However, several changes - SquashFS, disabling unused file-systems, enable timestamp in printk and most importantly adding the above advanced options - are lost! If I run menuconfig again, I see that they are missing. ... It appears that specific kernel config options - not all - are overwritten as part of each build.
How do I stop this behavior and force my changes to be included in the new kernel?
Thanks!
Trevor
