From: Stephen Boyd <swboyd@chromium.org> To: Aaron Durbin <adurbin@chromium.org>, Julius Werner <jwerner@chromium.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, LKML <linux-kernel@vger.kernel.org>, Wei-Ning Huang <wnhuang@chromium.org>, Julius Werner <jwerner@chromium.org>, Brian Norris <briannorris@chromium.org>, samuel@sholland.org Subject: Re: [PATCH v3 5/7] firmware: coreboot: Remap RAM with memremap() instead of ioremap() Date: Thu, 09 Aug 2018 15:07:37 -0700 [thread overview] Message-ID: <153385245791.220756.10097093170204882190@swboyd.mtv.corp.google.com> (raw) In-Reply-To: <CAODwPW8x=ghbVpo4q48jh-xGScP+2O_Vt7LTtSqhLvAAnCVXuA@mail.gmail.com> Quoting Julius Werner (2018-08-09 11:24:29) > One thing to note is that we still want this space to be mappable by > userspace applications via /dev/mem, so we need to make sure that > there's no weird memory type mismatch that causes problems with that. > Adding Aaron to see if he has any concerns here, since I think he's > seen something like that in the past (not sure if it was related to > what this kernel driver does). > > Can you please test this on an x86 Chromebook and run the 'cbmem' > userspace utility, make sure it doesn't fail after this? Sure! > > Also, stupid question after taking a step back and looking at this > again: why do we keep a mapping alive for the lifetime of the driver > at all? It used to be necessary when this driver was > find-entry-on-demand, but nowadays it just goes through all entries > once at probe time and immediately memcpy_fromio()s out all the > relevant information into (struct coreboot_device)s. After that we're > done accessing the "real" coreboot table, forever. Why not just unmap > it again at the end of coreboot_table_init()? Yes, we just copy everything over so it makes it simpler to just unmap at the end of coreboot_table_init(). Then userspace is free to make a questionable mapping into system RAM to find the table itself. I'll make this change.
next prev parent reply other threads:[~2018-08-09 22:07 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-08-09 17:17 [PATCH v3 0/7] firmware: coreboot: Fix probe and simplify code Stephen Boyd 2018-08-09 17:17 ` [PATCH v3 1/7] firmware: coreboot: Let OF core populate platform device Stephen Boyd 2018-08-09 17:31 ` Brian Norris 2018-08-09 17:17 ` [PATCH v3 2/7] firmware: coreboot: Unmap ioregion on failure Stephen Boyd 2018-08-09 17:49 ` Brian Norris 2018-08-09 19:40 ` Stephen Boyd 2018-08-09 19:52 ` Brian Norris 2018-08-09 23:25 ` Stephen Boyd 2018-08-09 17:17 ` [PATCH v3 3/7] firmware: coreboot: Make bus registration symmetric Stephen Boyd 2018-08-09 18:10 ` Julius Werner 2018-08-09 23:30 ` Stephen Boyd 2018-08-09 17:17 ` [PATCH v3 4/7] firmware: coreboot: Collapse platform drivers into bus core Stephen Boyd 2018-08-09 17:17 ` [PATCH v3 5/7] firmware: coreboot: Remap RAM with memremap() instead of ioremap() Stephen Boyd 2018-08-09 18:24 ` Julius Werner 2018-08-09 22:07 ` Stephen Boyd [this message] 2018-08-09 17:17 ` [PATCH v3 6/7] firmware: coreboot: Only populate devices in coreboot_table_init() Stephen Boyd 2018-08-09 21:02 ` Julius Werner 2018-08-09 23:43 ` Stephen Boyd 2018-08-09 17:17 ` [PATCH v3 7/7] firmware: coreboot: Request table region for exclusive access Stephen Boyd 2018-08-09 21:07 ` Julius Werner 2018-08-09 23:03 ` Stephen Boyd 2018-08-09 23:37 ` Julius Werner 2018-08-09 23:44 ` Julius Werner 2018-08-10 2:54 ` Stephen Boyd 2018-08-10 23:24 ` Stephen Boyd 2018-08-09 18:03 ` [PATCH v3 0/7] firmware: coreboot: Fix probe and simplify code Brian Norris
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