Messages in this thread | | | Date | Thu, 4 Feb 2010 14:18:20 -0500 | Subject | Re: hung bootup with "drm/radeon/kms: move radeon KMS on/off switch out of staging." | From | Alex Deucher <> |
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On Thu, Feb 4, 2010 at 2:06 PM, Ingo Molnar <mingo@elte.hu> wrote: > > * Alex Deucher <alexdeucher@gmail.com> wrote: > >> On Thu, Feb 4, 2010 at 1:12 PM, Ingo Molnar <mingo@elte.hu> wrote: >> > >> > * Matthew Garrett <mjg59@srcf.ucam.org> wrote: >> > >> >> On Thu, Feb 04, 2010 at 06:54:45PM +0100, Ingo Molnar wrote: >> >> >> >> > But you could claim that it's not a regression because 1) technically the >> >> > code got introduced in drivers/staging/, and staging drivers are not on >> >> > the regression list 2) the Kconfig value is default-off so it can only >> >> > harm those who got lured by a new Kconfig value popping up in -rc7 in a >> >> > well working driver they already have enabled. >> >> > >> >> > So the moving of driver functionality from drivers/staging/ to drivers/ >> >> > is a grey area it appears. Wouldnt it have been better to do this in the >> >> > next merge window, as all other drivers do? It's not new hardware >> >> > enablement either, it's feature enablement for an existing driver. >> >> >> >> The reason the option was in staging (as has been mentioned before) was >> >> because the ABI wasn't felt to be stable enough. Upstream is now willing to >> >> commit to that stability, so now seems as good a time to move it as any. >> >> There's no code change and there's no default configuration change, so I >> >> really can't see any way that it can be classed as a regression. >> > >> > But that argument in essence renders the regression policy meaningless for >> > such code: just about any new driver feature under the sun could be shaped as >> > a Kconfig option, introduced via a drivers/staging Kconfig entry, and then >> > activated via a twoliner commit in a later -rc. >> > >> > IMHO the point of tracking regressions is to reduce the bugginess of the >> > kernel and thus to help users, not to give ground for legalistic arguments. >> > >> > There _are_ common-sense exceptions from the regression rules, such as the >> > introduction of a new piece of hardware that was previously unsupported >> > (hence there's no expectation of stability) - but the tweaking of an >> > existing, widely used driver (even if the new opion is default-off) hardly >> > seems to qualify for that. >> > >> >> This is a completely new driver. It's only part of the existing drm for >> compatibility reasons. It requires an entirely different graphics stack >> above it and works very differently from the old drm stack. > > Will the user know? IMHO what matters in the end is user expectation. > > Lets walk through what a current kernel tester of the drm/radeon driver sees > when he types 'make oldconfig' after installing the (to-be-released) .33-rc7 > kernel. Firstly, the user with a brand-new distro already has this enabled: > > CONFIG_DRM_RADEON=y > > and knows the driver, and it performs adequately. Then in -rc7 he gets a new > option: > > ATI Radeon (DRM_RADEON) [Y/n/?] y > Enable modesetting on radeon by default (DRM_RADEON_KMS) [N/y/?] (NEW) > > The user might easily go: "Hey this is a driver i already have, and there's a > new sub-option for this well-working driver. Sure, enable it, these kernel > folks know what they are doing and i rarely see any crashes past -rc2 > kernels." > > Does this new option tell him what you just told me, that: > > > This is a completely new driver. It's only part of the existing drm for > > compatibility reasons. It requires an entirely different graphics stack > > above it and works very differently from the old drm stack. > > ? > > it doesnt. Even if he types '?', it tells: > > CONFIG_DRM_RADEON_KMS: > > Choose this option if you want kernel modesetting enabled by default, > and you have a new enough userspace to support this. Running old > userspaces with this enabled will cause pain. > > The user will likely go "cool I have a fresh distro with recent Xorg, lets > try it". >
And if it crashes, he'll report a bug and we'll fix it.
Alex
> If this is really a brand new driver essentially fresh out of > drivers/staging/ in -rc7 you should be abundantly clear about that in the > Kconfig help text - that it's a brand new driver and that it might crash on > bootup, etc. > > Thanks, > > Ingo > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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