Re: [PATCH] drm/xe/xe_survivability: Add support for survivability mode v2

[Raag Jadav <raag.jadav@intel.com>]

On Sun, Oct 19, 2025 at 05:55:17PM +0200, Raag Jadav wrote:
> On Thu, Oct 16, 2025 at 03:17:54PM -0400, Rodrigo Vivi wrote:
> > On Tue, Oct 14, 2025 at 11:02:58AM +0530, Riana Tauro wrote:
> > > v2 survivability breadcrumbs introduces a new mode called
> > > SPI Flash Descriptor Override mode (FDO). This is enabled by
> > > PCODE when MEI itself fails and firmware cannot be updated via
> > > MEI using igsc. This mode provides the ability to update
> > > the firmware directly via SPI driver.
> > > 
> > > Xe KMD initializes the nvm aux driver if FDO mode is enabled.
> > > 
> > > Userspace should check FDO mode entry in survivability sysfs before
> > > using the SPI driver to update firmware.
> > > 
> > > v2 also supports survivability mode for critical boot errors.
> > > 
> > > 	cat /sys/bus/pci/devices/0000\:03\:00.0/survivability_mode
> > > 
> > >                Capability Info: 0x138320 - 0x2001ae06
> > >                Postcode Info: 0x138324 - 0x0
> > >                Overflow Info: 0x138328 - 0x0
> > >                Auxiliary Info 0: 0x13832c - 0x0
> > 
> > I am truly sorry here, but although I was the one that designed this,
> > looking it now, I realized that this is breaking the sysfs rules
> > of one value per file and no fancy format. This is only allowed in
> > the debugfs.
> > 
> > We need to change this asap, and with help from any tool that
> > might be already consuming this.
> > 
> > >                FDO Mode: enabled
> > 
> > After we fix that we can come and add this.
> > 
> > About our options: I don't believe that debugfs is an option
> > without the drm card right?
> > 
> > Perhaps what we need is to transform survivability_mode in
> > the directory. Each entry becomes a file in this directory.
> > 
> > Sorry,
> > Rodrigo.
> 
> Tried discussing in this direction[1], but not very convincingly I guess.
> 
> [1] https://lore.kernel.org/intel-xe/aIDrCMRK2gPGmIs6@black.fi.intel.com/

Documentation/filesystems/configfs.rst +61

* Normal attributes, which similar to sysfs attributes, are small ASCII text
  files, with a maximum size of one page (PAGE_SIZE, 4096 on i386).  Preferably
  only one value per file should be used, and the same caveats from sysfs apply.

So this also puts some of our configfs attributes in the same position, but
I'll let the maintainers have final call on this.

Raag
> 
> Raag