On Tue, 20 May 2008 22:24:01 +0200 Marcin Krol <hawk@xxxxxxxxxxxxx> wrote: > >> --- linux-2.6.25/drivers/block/brd.c.orig 2008-04-17 04:49:44.000000000 +0200 > >> +++ linux-2.6.25/drivers/block/brd.c 2008-05-18 01:18:28.381903343 +0200 > >> @@ -442,6 +442,7 @@ > >> disk->fops = &brd_fops; > >> disk->private_data = brd; > >> disk->queue = brd->brd_queue; > >> + disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO; > >> sprintf(disk->disk_name, "ram%d", i); > >> set_capacity(disk, rd_size * 2); > >> > > > > Why is it a "regression"? > > > > The change in 2.6.25 was a back-compatible one. > > > > This change is not a back-compatible one and if we're going to now > > withdraw the newly-added 2.6.25 feature then we should also withdraw it > > from 2.6.26.x and 2.6.25.x (if that is still under maintenance). To > > reduce the incidence of "hey where did my feature go" problems. > > > > Really, life would be simpler if we just left the accidentally-added > > feature in place. What problems does it cause? > > All kernels prior to 2.6.25 weren't displaying ramdisks in > /proc/partitions. Since there are many userspace tools using infromation > from /proc/partitions some of them may now behave incorrectly (I didn't > tested any though). For example before 2.6.25 /proc/partitions was empty > if no block devices like hard disks and such were detected by kernel. > Now all 16 ramdisks are always visible there. Some software may rely on > such information (I mean, on empty /proc/partitions). > > There was quite similar situation back in 2004, and ramdisks were > excluded back from displaying. Thats why I called this a regression > (maybe a bit unfortunate). See this patch for info: > http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.3-rc2/2.6.3-rc2-mm1/broken-out/nbd-proc-partitions-fix.patch > > I also think that someone somewhere (long time ago) excluded ramdisks > from /proc/partitions for good reasons. It is possible that now such new > "feature" is harmless, but I think there are more chances that someone > will say "hey, /proc/partitions has changed, now my software doesn't > work" then "hey where did my new 2.6.25 feature go". nbd devices are > also excluded, maybe for very same (unknown to me) reasons. I added the above info to the changelog. But it's still a bit vague, and as far as I know we don't actually know about any breakage (do we?) > For me this change isn't problematic. Yes, it did broken my software and > yes, I could fix my software but since its working only on specific > kernels (precompiled by me) I've chosen to revert kernel change instead > to get old behaviour. Ah, it only affects 2.6.25.x and no earlier -stable kernels. Not so bad. Greg, Chris? Thoughts? -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
