[OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
I've spent few hours today trying to understand extroot. I've failed :( Of course I was trying to use wiki pages: http://wiki.openwrt.org/doc/howto/extroot http://wiki.openwrt.org/doc/uci/fstab 1) Main question Is the following sentence true at all? The configuration of extroot is very simple and is done entirely in /etc/config/fstab. It seems that /etc/init.d/fstab uses block umount and block mount only. I was reading the source code (fstools-2014-12-15/block.c) and it seems that block mount doesn't really handle extroot at all. I think some kind of extroot support is provided in block extroot, but I don't fully understand it. It seems to be looking for partitions rootfs and then rootfs_data ignoring whatever is set in /etc/config/fstab. If mount extroot is really supposed to be used, is there any way to point some external device (without MTD partitions) as extroot? I got confused. 2) UBI and UBIFS support I guess it's too new to be documented and I don't understand it much from the code. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
On 16/12/2014 11:23, Gergely Kiss wrote: Hi Rafał, please allow me to comment on your 2nd point as I was the one who recently published the patch to make extroot functionality work with UBIFS. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. That's correct. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? I'm not sure I understand what you mean here. Are there any devices out there with multiple flash chips on-board? As far as I know, UBI cannot work on top of block devices (eg. USB flashes, SD cards), only raw flash chips so I can't really imagine what exact use-case you mean. Could you please clarify? Thanks, Gergely On 16 December 2014 at 11:00, Rafał Miłecki zaj...@gmail.com wrote: I've spent few hours today trying to understand extroot. I've failed :( Of course I was trying to use wiki pages: http://wiki.openwrt.org/doc/howto/extroot http://wiki.openwrt.org/doc/uci/fstab 1) Main question Is the following sentence true at all? The configuration of extroot is very simple and is done entirely in /etc/config/fstab. It seems that /etc/init.d/fstab uses block umount and block mount only. I was reading the source code (fstools-2014-12-15/block.c) and it seems that block mount doesn't really handle extroot at all. I think some kind of extroot support is provided in block extroot, but I don't fully understand it. It seems to be looking for partitions rootfs and then rootfs_data ignoring whatever is set in /etc/config/fstab. If mount extroot is really supposed to be used, is there any way to point some external device (without MTD partitions) as extroot? I got confused. 2) UBI and UBIFS support I guess it's too new to be documented and I don't understand it much from the code. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel Hi, I think this is where this discussion started and Rafal explains a bit more about the hardware: https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html Regards, Flavio ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
Sorry, I haven't read that post earlier. So, is this simply about mounting an additional UBIFS partition at boot time? If so, I believe the best solution would be to extend the functionality of fstab with a simple (shell) script, as suggested in the fstab wiki: BTRFS, JFS, *UBI* [...] are not supported in /etc/config/fstab. Use manual scripting. Would that be possible? Regards, Gergely On 16 December 2014 at 14:39, Flávio Silveira f...@terra.com.br wrote: On 16/12/2014 11:23, Gergely Kiss wrote: Hi Rafał, please allow me to comment on your 2nd point as I was the one who recently published the patch to make extroot functionality work with UBIFS. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. That's correct. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? I'm not sure I understand what you mean here. Are there any devices out there with multiple flash chips on-board? As far as I know, UBI cannot work on top of block devices (eg. USB flashes, SD cards), only raw flash chips so I can't really imagine what exact use-case you mean. Could you please clarify? Thanks, Gergely On 16 December 2014 at 11:00, Rafał Miłecki zaj...@gmail.com wrote: I've spent few hours today trying to understand extroot. I've failed :( Of course I was trying to use wiki pages: http://wiki.openwrt.org/doc/howto/extroot http://wiki.openwrt.org/doc/uci/fstab 1) Main question Is the following sentence true at all? The configuration of extroot is very simple and is done entirely in /etc/config/fstab. It seems that /etc/init.d/fstab uses block umount and block mount only. I was reading the source code (fstools-2014-12-15/block.c) and it seems that block mount doesn't really handle extroot at all. I think some kind of extroot support is provided in block extroot, but I don't fully understand it. It seems to be looking for partitions rootfs and then rootfs_data ignoring whatever is set in /etc/config/fstab. If mount extroot is really supposed to be used, is there any way to point some external device (without MTD partitions) as extroot? I got confused. 2) UBI and UBIFS support I guess it's too new to be documented and I don't understand it much from the code. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel Hi, I think this is where this discussion started and Rafal explains a bit more about the hardware: https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html Regards, Flavio ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
On Tue, 16 Dec 2014 16:06:27 +0100, Gergely Kiss mail.g...@gmail.com wrote: Please don't top-post. Sorry, I haven't read that post earlier. So, is this simply about mounting an additional UBIFS partition at boot time? If so, I believe the best solution would be to extend the functionality of fstab with a simple (shell) script, as suggested in the fstab wiki: BTRFS, JFS, *UBI* [...] are not supported in /etc/config/fstab. Use manual scripting. Would that be possible? Regards, Gergely On 16 December 2014 at 14:39, Flávio Silveira f...@terra.com.br wrote: On 16/12/2014 11:23, Gergely Kiss wrote: Hi Rafał, please allow me to comment on your 2nd point as I was the one who recently published the patch to make extroot functionality work with UBIFS. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. That's correct. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? I'm not sure I understand what you mean here. Are there any devices out there with multiple flash chips on-board? As far as I know, UBI cannot work on top of block devices (eg. USB flashes, SD cards), only raw flash chips so I can't really imagine what exact use-case you mean. Could you please clarify? Thanks, Gergely On 16 December 2014 at 11:00, Rafał Miłecki zaj...@gmail.com wrote: I've spent few hours today trying to understand extroot. I've failed :( Of course I was trying to use wiki pages: http://wiki.openwrt.org/doc/howto/extroot http://wiki.openwrt.org/doc/uci/fstab 1) Main question Is the following sentence true at all? The configuration of extroot is very simple and is done entirely in /etc/config/fstab. It seems that /etc/init.d/fstab uses block umount and block mount only. I was reading the source code (fstools-2014-12-15/block.c) and it seems that block mount doesn't really handle extroot at all. I think some kind of extroot support is provided in block extroot, but I don't fully understand it. It seems to be looking for partitions rootfs and then rootfs_data ignoring whatever is set in /etc/config/fstab. If mount extroot is really supposed to be used, is there any way to point some external device (without MTD partitions) as extroot? I got confused. 2) UBI and UBIFS support I guess it's too new to be documented and I don't understand it much from the code. It seems that if there isn't rootfs MTD partition, then the code will look for rootfs UBI volume. The same applies to the rootfs_data. But what if my serial flash contains rootfs + rootfs_data partitions and I still want to use some UBI volume on another flash (NAND one)? -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel Hi, I think this is where this discussion started and Rafal explains a bit more about the hardware: https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html Regards, Flavio Rafal, what about mtdconcat? Imre ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
On 16 December 2014 at 16:30, Imre Kaloz ka...@openwrt.org wrote: On Tue, 16 Dec 2014 16:06:27 +0100, Gergely Kiss mail.g...@gmail.com wrote: On 16 December 2014 at 14:39, Flávio Silveira f...@terra.com.br wrote: On 16/12/2014 11:23, Gergely Kiss wrote: I'm not sure I understand what you mean here. Are there any devices out there with multiple flash chips on-board? As far as I know, UBI cannot work on top of block devices (eg. USB flashes, SD cards), only raw flash chips so I can't really imagine what exact use-case you mean. Could you please clarify? I think this is where this discussion started and Rafal explains a bit more about the hardware: https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html Rafal, what about mtdconcat? That would be nice because I could use space available on the serial flash. So far I assumed to ignore that extra ~10 MiB and focus on NAND mostly. However I'm not sure if this will be possible without heavy changes. I have rootfs_data (JFFS2) partition on serial flash. I would need to concat it with my UBI partition on NAND flash. 1) I'm afraid it may be complex to change the way OpenWrt treats rootfs_data. It's coded in many places. 2) Concanation has to be handled in the kernel. There isn't any DT driver I could use for bcm53xx. Guess I'd need to write once 3) I have no idea if UBI can work well on concan-ated partition. In theory yes, but in practice? UBI cares pretty much about wearing I believe. -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
On 16 December 2014 at 16:06, Gergely Kiss mail.g...@gmail.com wrote: So, is this simply about mounting an additional UBIFS partition at boot time? If so, I believe the best solution would be to extend the functionality of fstab with a simple (shell) script, as suggested in the fstab wiki: BTRFS, JFS, *UBI* [...] are not supported in /etc/config/fstab. Use manual scripting. Would that be possible? I could implement that, but is it going to help? This block extroot is really confusing for me. Does it really look for entries in /etc/config/fstab? Or does it hardcode to use rootfs / rootfs_data partitions? Could you explain what's the point of all these find_block_mtd(rootfs, fs, sizeof(fs)); find_block_ubi_RO(libubi, rootfs, fs, sizeof(fs)); find_block_mtd(rootfs_data, fs_data, sizeof(fs_data)); find_block_ubi(libubi, rootfs_data, fs_data, sizeof(fs_data)); in the main_extroot? Also, in my case there is rootfs_data MTD partition. I could create UBI volume rootfs_data on NAND flash, but block extroot will still pick the MTD partition. ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Current state of extroot, how to use it, what about ubi(fs)
On 12/16/2014 07:35 PM, Rafał Miłecki wrote: Does it really look for entries in /etc/config/fstab? Or does it hardcode to use rootfs / rootfs_data partitions? Could you explain what's the point of all these find_block_mtd(rootfs, fs, sizeof(fs)); find_block_ubi_RO(libubi, rootfs, fs, sizeof(fs)); find_block_mtd(rootfs_data, fs_data, sizeof(fs_data)); find_block_ubi(libubi, rootfs_data, fs_data, sizeof(fs_data)); in the main_extroot? To be the honest, I'm not very familiar with the sources, I only made some slight enhancements to a patch created by a forum member, see https://forum.openwrt.org/viewtopic.php?pid=257518#p257518 Maybe the developer who wrote the code originally could answer that. I suspect those functions are there so in case extroot fails, the code can revert to the flash partition to avoid having an unbootable system. Not sure of you read already but the bottom of this article might help understanding the logic: http://wiki.openwrt.org/doc/howto/extroot/extroot.theory Also, in my case there is rootfs_data MTD partition. I could create UBI volume rootfs_data on NAND flash, but block extroot will still pick the MTD partition. Well, that's how it works now but you can always create a patch if you want to change that behaviour. Regards, Gergely ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
