From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-yk0-x22d.google.com ([2607:f8b0:4002:c07::22d]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZhLVU-00077h-Ow for barebox@lists.infradead.org; Wed, 30 Sep 2015 17:49:33 +0000 Received: by ykdt18 with SMTP id t18so51837169ykd.3 for ; Wed, 30 Sep 2015 10:49:11 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20150930071916.GZ7858@pengutronix.de> References: <1443362931-1881-1-git-send-email-vicencb@gmail.com> <20150929070523.GP7858@pengutronix.de> <20150930071916.GZ7858@pengutronix.de> Date: Wed, 30 Sep 2015 18:49:11 +0100 Message-ID: From: vj List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] xload: be more flexible when searching for second stage bootloader. To: Sascha Hauer Cc: barebox@lists.infradead.org On Wed, Sep 30, 2015 at 8:19 AM, Sascha Hauer wrote: > On Tue, Sep 29, 2015 at 08:06:35PM +0100, vj wrote: >> On Tue, Sep 29, 2015 at 8:05 AM, Sascha Hauer wrote: >> > On Sun, Sep 27, 2015 at 03:08:51PM +0100, Vicente Bergas wrote: >> >> A first stage bootloader can read fat and ext4 filesystems, and >> >> even both can be compiled-in at the same time. >> >> But then xload has a hardcoded fat filesystem mount option which >> >> renders ext4 unusable. >> >> This patch tries to mount it as ext4 if the fat attempt fails. >> >> >> >> Then, a typical use case of an ext4 formatted filesystem >> >> is it to be a standard linux filesystem, which contains >> >> boot-related files in /boot. So, when searching for the second stage >> >> bootloader, try /boot/barebox.bin after not finding it in /barebox.bin >> >> >> >> Signed-off-by: Vicente Bergas >> >> --- >> >> arch/arm/mach-omap/xload.c | 4 ++++ >> >> 1 file changed, 4 insertions(+) >> >> >> >> diff --git a/arch/arm/mach-omap/xload.c b/arch/arm/mach-omap/xload.c >> >> index ebcbcbc..c5e29f8 100644 >> >> --- a/arch/arm/mach-omap/xload.c >> >> +++ b/arch/arm/mach-omap/xload.c >> >> @@ -118,6 +118,8 @@ static void *omap_xload_boot_mmc(void) >> >> partname = asprintf("%s.0", diskdev); >> >> >> >> ret = mount(partname, "fat", "/", NULL); >> >> + if (ret) >> >> + ret = mount(partname, "ext4", "/", NULL); >> > >> > It should also be possible to pass NULL as fs type in which case we >> > automatically detect the fs type. Could you check that? >> >> I didn't know that. This way it would be nicer and cleaner! >> So it has been tested but it didn't work :( >> mount calls detect_fs, detect_fs calls file_name_detect_type and >> file_name_detect_type calls open. >> open fails to open the "mmc0.0" file name > > Ok, I see. This indeed can't work as it depends on devfs being mounted > on /dev/. For this to work we would need a cdev_detect_filetype(const > char *name) which uses the cdev_* operations to read a buffer and pass > that to file_detect_type(). You're invited to implement that ;) > >> So, the first 128KB block can hold an MBR plus partition table, then a >> raw image of the MLO file can be present at offset 128KB followed by >> the disk partitions. >> >> In section 26.1.7.5.3 page 4939 figure 26-17 MMC/SD Booting >> states that raw mode detection is performed before searching for the >> MLO file in a filesystem. >> >> All in all, it is possible to have a "fat-free" SD-card. > > Now that you say it I remember having read about this before. > > Does this work well with the rest of barebox? In omap_env_init() we > mount the first mmc partition to /boot and put the environment to > /boot/barebox.env. That doesn't work when the first partition doesn't > contain a FAT. Do you put your environment somewhere else? I was not using the environment save/restore feature and was unaware that it was broken. The environment retrieval could be improved in a similar way: try mounting all supported filesystems and search in "mountpoint/" and "mountpoint/boot/" But the environment save feature can't be easily supported on ext4 because the driver does not support writes. Still I think that this patch is an improvement, is not the patch itself that broke the env save/restore, it was a new use case enabled by it. > > Sascha > > -- > Pengutronix e.K. | | > Industrial Linux Solutions | http://www.pengutronix.de/ | > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox