Hi Tom,
-----Original Message----- From: U-Boot u-boot-bounces@lists.denx.de On Behalf Of Tom Rini Sent: Saturday, January 30, 2021 12:53 AM To: Wasim Khan (OSS) wasim.khan@oss.nxp.com Cc: sjg@chromium.org; t-kristo@ti.com; Varun Sethi V.Sethi@nxp.com; u- boot@lists.denx.de Subject: Re: [PATCH] cmd: fdt: skip board specific fixup using env variable
On Thu, Jan 28, 2021 at 08:15:33AM +0000, Wasim Khan (OSS) wrote:
Hi Tom,
-----Original Message----- From: Tom Rini trini@konsulko.com Sent: Wednesday, January 27, 2021 7:41 PM To: Wasim Khan (OSS) wasim.khan@oss.nxp.com Cc: sjg@chromium.org; t-kristo@ti.com; Varun Sethi V.Sethi@nxp.com; u- boot@lists.denx.de; Wasim Khan wasim.khan@nxp.com Subject: Re: [PATCH] cmd: fdt: skip board specific fixup using env variable
On Wed, Jan 27, 2021 at 02:09:48PM +0100, Wasim Khan wrote:
From: Wasim Khan wasim.khan@nxp.com
Sometimes it is useful to boot OS with already fixed-up device tree. Check for env variable 'skip_board_fixup' before calling ft_board_setup(). Current behaviour is unchanged, additionally user can set skip_board_fixup to 1 to skip the fixup.
Signed-off-by: Wasim Khan wasim.khan@nxp.com
common/image-fdt.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
Can you provide a specific example or two here? Thanks!
Thank you for your comments.
Recently I faced issue where Linux crash in PCIe was observed in customer's
env.
Whereas same Linux was booting fine in my environment. After debugging
we found that U-boot was doing fixup based on SVR value. SVR check was failing in customer's env because of different SoC personality which was causing the crash in OS.
So I thought it is good idea to have an option to bypass U-boot fixup and use
an already fixed-up device tree so that we can quickly check if the problem is in OS or it is caused because of missed/wrong fixup from Uboot.
Another use case I can think of is suppose if we want to introduce a new dtb
fixup , we can directly add the change in a fixed-up device tree, do all experiments and once validated thoroughly , we can do the same change via Uboot fixup.
OK, I can see how this can be useful in some circumstances, thanks. What I'd like to see is updating checkpatch.pl to have a check that we aren't setting this by default in environments (something like the check that exists now for (fdt|initrd)_high=0xffffffff should be a good reference) as my worry is that someone will decide that's how to work-around some issue and we'll end up in another nightmare down the road of uncorrected dtbs causing other problems. Thanks!
-- Tom
Thanks, If I understood your comment correctly, you suggesting to add 'skip_board_fixup' to CONFIG_EXTRA_ENV_SETTINGS for all of our platforms and check its default value in checkpatch.pl , which must be 0 ?