Diff for /wikisrc/ports/evbarm/raspberry_pi.mdwn between versions 1.76 and 1.77

version 1.76, 2018/10/30 14:28:28 version 1.77, 2018/10/30 14:35:31
Line 159  The device boots by finding a file "boot Line 159  The device boots by finding a file "boot
   
 The standard approach is to use a uSD card, with a fdisk partition table containing a FAT32 partition marked active, and a NetBSD partition.  The NetBSD partition will then contain a disklabel, pointing to an FFS partition (a), a swap paritiion (b) and the FAT32 boot partition mounted as /boot (e).  The file /boot/cmdline.txt has a line to set the root partition.  The standard approach is to use a uSD card, with a fdisk partition table containing a FAT32 partition marked active, and a NetBSD partition.  The NetBSD partition will then contain a disklabel, pointing to an FFS partition (a), a swap paritiion (b) and the FAT32 boot partition mounted as /boot (e).  The file /boot/cmdline.txt has a line to set the root partition.
   
 One wrinkle in the standard approach is that the disk layout is "boot swap /", but the NetBSD fdisk partition starts at the location of /.   The / partition can hold a disklabel, while swap cannot.   It is normal to have swap after /, but this arrangement permits growing / on first boot, for the typical case where a larger uSD is used.  One wrinkle in the standard approach is that the disk layout is "boot swap /", but the NetBSD fdisk partition starts at the location of /.   The / partition can hold a disklabel, while swap cannot.   It is normal to have swap after / (and thus within the fdisk partition), but the arrangement used permits growing / on first boot, for the typical case where a larger uSD is used, compared to the minimum image size.
   
 An alternate approach is to have the boot FAT32 partition as above, but to have the entire system including root on an external disk.  This is configured by changing root=ld0a to root=sd0a or root=dk0 (depending on disklabel/GPT).  Besides greateer space, part of the point is to avoid writing to the uSD card.  An alternate approach is to have the boot FAT32 partition as above, but to have the entire system including root on an external disk.  This is configured by changing root=ld0a to root=sd0a or root=dk0 (depending on disklabel/GPT).  Besides greater space, part of the point is to avoid writing to the uSD card.
   
 A third approach, workable on the Pi 3 only, is to configure USB host booting (already enableed on the 3+) see the upstream documentation) and have the boot partition also on the external device.  In this case the external device must be configured via fdisk because the hardware's first-stage boot does not have GPT support.   \todo Explain if this has been observed to work.  A third approach, workable on the Pi 3 only, is to configure USB host booting (already enableed on the 3+) see the upstream documentation) and have the boot partition also on the external device.  In this case the external device must be configured via fdisk because the hardware's first-stage boot does not have GPT support.   \todo Explain if this has been observed to work.
 \todo Explain if the [[procedure to program USB host boot mode|https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md]] can function under NetBSD; the examples on the web use Raspbian.  \todo Explain if the [[procedure to program USB host boot mode|https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md]] can function under NetBSD; the examples on the web use Raspbian.

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  Added in v.1.77


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