From mboxrd@z Thu Jan 1 00:00:00 1970 To: Daniel Wu Cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: Using zImage.initrd In-reply-to: Your message of "Fri, 09 Jun 2000 08:38:20 +1000" <00Jun9.083821est.115346@border.alcanet.com.au> Mime-Version: 1.0 Content-Type: text/plain Date: Fri, 09 Jun 2000 12:40:30 +1000 Message-ID: <27066.960518430@msa.cmst.csiro.au> From: Murray Jensen Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: On Fri, 9 Jun 2000 08:38:20 +1000, Daniel Wu writes: >Does anyone what the difference between making a kernel with "make zImage" and >"Make zImage.initrd"? - Apart from the obvious fact that the later builds a >kernel which expects the rootfs to be on the RAM disk. Firstly, you need to select both CONFIG_BLK_DEV_RAM and CONFIG_BLK_DEV_INITRD to build zImage.initrd. Secondly, you need a file in arch/ppc/mbxboot called ramdisk.image.gz. When you build zImage.initrd, the secondary boot loader is re-compiled with INITRD_OFFSET and INITRD_SIZE set, which are used to locate the start and end of the ramdisk.image.gz file in memory. The start and end are passed to the kernel in registers (r4/r5??), which it saves into the variables initrd_start and initrd_end. The secondary boot loader also changes the kernel command line arguments so that root=/dev/ram instead of root=/dev/nfs. The kernel does various things if initrd_start is non-zero, but the main one is to decompress the ramdisk.image.gz data into ramdisk 0, and because root=/dev/ram, this is then mounted as the root filesystem. Others can point out anything I have left out - I tried my best :-) >The crash location is in the __wake_up function according to the map. Try this patch: --- fs/buffer.c 2000/05/16 01:31:41 1.1.1.12 +++ fs/buffer.c 2000/06/02 04:26:16 @@ -2336,7 +2336,7 @@ { DECLARE_WAITQUEUE(wait, current); - if (current == bdflush_tsk) + if (bdflush_tsk == 0 || current == bdflush_tsk) return; if (!block) { It is against the 2.3.x kernel, but I think it should apply to the 2.2.x kernel ok. Cheers! Murray... -- Murray Jensen, CSIRO Manufacturing Sci & Tech, Phone: +61 3 9662 7763 Locked Bag No. 9, Preston, Vic, 3072, Australia. Fax: +61 3 9662 7853 Internet: Murray.Jensen@cmst.csiro.au (old address was mjj@mlb.dmt.csiro.au) ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/