[meta-xilinx] [meta-xilinx-community][PATCH 1/7] microzed-zynq7: Update machine configuration

[Nathan Rossi]

> -----Original Message-----
> From: David Andrey [mailto:David.Andrey at netmodule.com]
> Sent: Tuesday, November 11, 2014 4:57 PM
> To: Nathan Rossi; meta-xilinx at lists.yoctoproject.org
> Cc: Elvis Dowson
> Subject: RE: [meta-xilinx-community][PATCH 1/7] microzed-zynq7: Update
> machine configuration
> 
> Hi Nathan,
> 
> > * Remove Kernel and U-Boot version specifiers, rely on
> >   machine-xilinx-default.inc to provide these
> 
> OK
> 
> > * Remove MACHINE_KCONFIG fragments
> > * blk-dev-ram.cfg - this is unnessecary, for a large ramdisk rootfs the
> >   initramfs kernel feature is more optimal (use the .cpio rootfs, or
> >   cpio.gz.u-boot for u-boot wrapped)
> 
> Doesn't understand very well why this should be a problem. initramfs and
> ramdisk
> are different things ?!

Sorry that should say "ramfs" not "initramfs". Have a read of the kernel documentation around ramdisk/ramfs. They are different but ramfs can be very useful as a replacement for a ramdisk, as having to configure the kernel every time the rootfs size increases can get tedious. Picking a default /dev/ram sizing is always tricky because it depends not only on how big the ramdisk is at boot, but also how much extra space in using during runtime as well as how much memory is available.

https://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt

However I am inclined to think that increasing the default value to 32768 in the meta-xilinx configs (only for zynq) might be a better solution in the case that larger ramdisk's are needed?

> 
> > * disable-net-cadence.cfg - macb should be used by default as it is
> >   mainline, alternatively the KERNEL_FEATURES variable can be used to
> >   override (from local.conf or elsewhere) the use of the macb driver
> >   with the "features/xilinx/disable-macb.scc" config fragment
> 
> Use of the xilinx driver seems more appropriate to me, at least for
> throughput. As you anyway use the Xilinx patched kernel, why do you
> rely on the cadence driver ?

The Xilinx driver is not mainline, which means disabling the MACB driver for all kernels essentially breaks linux-yocto kernels for this board. Is the only reason for your preference of the emacps driver its throughput?

To make it default for the microzed, disabling MACB for linux-xlnx kernels with something similar to below could be done to this patch.

KERNEL_FEATURES_pn-linux-xlnx += "features/xilinx/disable-macb.scc"

Regards,
Nathan

> 
> Regards
> David