Browse Source

Update docs/manual/about.md to describe the new partition layout

tags/alpha-Talos-II
Jonathan Currier 2 years ago
parent
commit
55510af747
1 changed files with 7 additions and 4 deletions
  1. +7
    -4
      docs/manual/about.md

+ 7
- 4
docs/manual/about.md View File

@@ -15,15 +15,17 @@ When modifying !BMC knowledge of [buildroot](http://buildroot.org) is very impor
The partition layout for currently support !BMC boards are (at this time) all the same.
* u-boot 384KiB (same as OpenBMC)
* u-boot-env 128KiB (same as OpenBMC)
* kernel 6MiB (Longer than OpenBMC)
* kernel-a 6MiB (Longer than OpenBMC)
* dev-data 1MiB
* rwfs 24.50MiB
* kernel-b 6MiB
* rwfs 18.50MiB

The first two partition are the same as OpenBMC (is someone is migrating off OpenBMC !BMC does not require changes. However any security patches will still be relevent). !BMC's kernel partion starts at the same offset as OpenBMC's, however it is longer.
The first two partition are the same as OpenBMC (if someone is migrating off OpenBMC !BMC does not require changes. However any security patches will still be relevent). !BMC's kernel-a partion starts at the same offset as OpenBMC's, however it is longer.
!BMC has a small 1MiB 'dev-data' squashfs partition for storing things like an RFD root password, device serial numbers, or any other information that should persist even in the even the rwfs is wiped. A valid dev-data partition is not required to boot if !BMC is unable to mount the squashfs it will simply skip it. However the lack of dev-data may result in undesirable security situations.
!BMC also has a second kernel patition, kernel-b. Systems can choose which to boot via u-boot env scripts. !BMC does not itself include u-boot, however an example is in the works.
The rwfs is a read/writeable jffs2 partition for persistent storage. It is also not required to boot.

At startup, the init script in the kernel initrd (embedded in the u-boot FIT image which lives in the 'kernel' partiton) will create an overlay like 'initrd,dev-data,rwfs' with the initrd being the bottom layer, and the rwfs being the top/modifiable layer.
At startup, the init script in the kernel initrd (embedded in the u-boot FIT image which lives in the 'kernel-a' or 'kernel-b' partiton) will create an overlay like 'initrd,dev-data,rwfs' with the initrd being the bottom layer, and the rwfs being the top/modifiable layer.
In the event the rwfs is not present, a portion of the initrd will be substitued for the top lay so that the rootfs remains read/writeable.
The dev-data partition will be skip if the script is unable to mount it.
If neither the dev-data nor the rwfs can be mounted the script will forgo the overlay and just use the initrd image.
@@ -37,6 +39,7 @@ building !BMC requires a buildroot repo (see the README.md for details).
make BR2_EXTERNAL=${PATH_TO_THIS_BR_EXTERNAL} O=${BUILD_DIR} blackbird-bmc_defconfig
make O=${BUILD_DIR}
```
For Talos II builds, replace blackbird-bmc_defconfig with talos-bmc_defconfig.

A 'dev-data' image, with a randomly generated root password, can be generated with:
```


Loading…
Cancel
Save