[SLOF] [PATCH v2] boot: do not use catpad to concatenate strings

[David Gibson]

On Thu, Dec 07, 2017 at 03:54:45PM +0530, Nikunj A Dadhania wrote:
> Thomas Huth <thuth at redhat.com> writes:
> 
> > On 01.12.2017 11:29, Nikunj A Dadhania wrote:
> >> The catpad size is 1K size, which can be hit easily hit with around 20 devices
> >> with bootindex.
> >> 
> >> Open code EVALUATE such that concatenation is not required. Replace usage of
> >> $cat with a 16K buffer allocated here.
> >> 
> >> Reported here: https://github.com/qemu/SLOF/issues/3
> >> 
> >> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
> >> 
> >> ---
> >> 
> >> qemu-system-ppc64 -nographic -nodefaults -serial stdio -monitor pty -m 2G \
> >> -device virtio-scsi-pci    \
> >> `for ((i=2;i<=50;i++)) ; \
> >> do echo -n "  -drive file=/tmp/storage$i.qcow2,if=none,id=drive$i,format=qcow2 \
> >> -device
> >> scsi-hd,drive=drive$i,id=disk$i,channel=0,scsi-id=0,lun=$i,bootindex=$i"; \
> >> done;` \
> >> -drive file=guest.disk,if=none,id=drv1,format=qcow2,cache=none \
> >> -device scsi-hd,drive=drv1,bootindex=1 -boot menu=on,splash-time=3000,strict=on
> >> ---
> >>  slof/fs/boot.fs | 30 +++++++++++++++++++++++++-----
> >>  1 file changed, 25 insertions(+), 5 deletions(-)
> >> 
> >> diff --git a/slof/fs/boot.fs b/slof/fs/boot.fs
> >> index 1fd7439..8a30195 100644
> >> --- a/slof/fs/boot.fs
> >> +++ b/slof/fs/boot.fs
> >> @@ -15,6 +15,9 @@
> >>  VARIABLE state-valid false state-valid !
> >>  CREATE go-args 2 cells allot go-args 2 cells erase
> >>  
> >> +4000 CONSTANT BOOT_DEV_SIZE
> >> +CREATE bootdev-buf BOOT_DEV_SIZE allot
> >
> > I somehow dislike the idea that we statically reserve such big arrays
> > ... would it be feasible to do this with alloc-mem on the fly instead?
> 
> Let me try that out

Don't try too hard.  I mean, sure a large static array is kinda ugly, but
when it comes down it the whole guest's memory is there with nothing
else to use it for until SLOF's done.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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