[RFE] Netboot of images bigger than 6Mb

Luis Machado luisgpm at linux.vnet.ibm.com
Thu Apr 26 22:46:17 EST 2007


Any comments on this?

Regards,
Luis
On Mon, 2007-04-23 at 20:50 -0300, Luis Machado wrote:
> Hi folks,
> 
> This is my first post to the yaboot-devel mailing list.
> 
> I've been using netboot with POWER machines for a while now and also
> have been struggling with the problem of having images bigger than 6Mb.
> 
> As a workaround, i decided to change yaboot a bit to make it download
> the images in a buffer up high in memory, above 40Mb. In this case we
> most probably would have a rather large block of free memory, making it
> possible to download the images. Also it would prevent us from hitting
> OF.
> 
> Since the kernel+ramdisk would be too big to fit in the memory area
> below 40Mb, probably hitting OF, we load the kernel high in memory also.
> 
> Today the kernel is being loaded at 20Mb. I changed that to 40Mb.
> 
> I've conducted tests with this configuration on P505's, OpenPower's,
> JS20's, JS21's and Intellistation machines and they all have worked
> fine.
> 
> I would need to test these modifications on Apple hardware as well.
> 
> Summary of changes:
> 
> Makefile:
> - KERNELADDR  = 0x01400000
> + KERNELADDR  = 0x02800000
> 
> Load the kernel+ramdisk higher in memory, here we try 40Mb.
> 
> second/fs_oc.c
> - #define LOAD_BUFFER_POS     0x600000
> + #define LOAD_BUFFER_POS     <new_value>
> 
> - #define LOAD_BUFFER_SIZE    0x600000
> + #define LOAD_BUFFER_SIZE    <new_value>
> 
> Change the download buffer size and buffer position in memory. The
> buffer size could by calculated dynamically based on the amount of data
> that has been downloaded or set to the limit of available memory above
> the position we have chosen. I believe the limit is 128Mb.
> 
> What do you think of this solution? Comments and suggestions are
> welcome.
> 
> Best regards,
> Luis
> 
> _______________________________________________
> Yaboot-devel mailing list
> Yaboot-devel at ozlabs.org
> https://ozlabs.org/mailman/listinfo/yaboot-devel




More information about the Yaboot-devel mailing list