[PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
From: wangwenhu When generating .config file with menuconfig on Freescale BOOKE SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of description in the Kconfig field, which makes it impossible to support L2Cache-Sram driver. Add a description to make it configurable. Signed-off-by: wangwenhu --- arch/powerpc/platforms/85xx/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/85xx/Kconfig b/arch/powerpc/platforms/85xx/Kconfig index fa3d29dcb57e..ee5ba10b98cb 100644 --- a/arch/powerpc/platforms/85xx/Kconfig +++ b/arch/powerpc/platforms/85xx/Kconfig @@ -17,7 +17,7 @@ if FSL_SOC_BOOKE if PPC32 config FSL_85XX_CACHE_SRAM - bool + bool "Freescale Cache-Sram" select PPC_LIB_RHEAP help When selected, this option enables cache-sram support -- 2.23.0
Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
发件人：Scott Wood 发送日期：2020-03-01 07:12:58 收件人："王文虎" 抄送人：wangwenhu ,Kumar Gala ,Benjamin Herrenschmidt ,Paul Mackerras ,Michael Ellerman ,linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org,triv...@kernel.org,Rai Harninder 主题：Re: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On Tue, 2020-01-21 at 14:38 +0800, 王文虎 wrote: >> 发件人：Scott Wood >> 发送日期：2020-01-21 13:49:59 >> 收件人："王文虎" >> 抄送人：wangwenhu ,Kumar Gala ,B >> enjamin Herrenschmidt ,Paul Mackerras < >> pau...@samba.org>,Michael Ellerman , >> linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, >> triv...@kernel.org,Rai Harninder >> 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On >> Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: >> > > From: Scott Wood >> > > Date: 2020-01-21 11:25:25 >> > > To: wangwenhu ,Kumar Gala < >> > > ga...@kernel.crashing.org>, >> > > Benjamin Herrenschmidt ,Paul Mackerras < >> > > pau...@samba.org>,Michael Ellerman , >> > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org >> > > Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < >> > > harninder@nxp.com> >> > > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM >> > > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: >> > > > > From: wangwenhu >> > > > > >> > > > > When generating .config file with menuconfig on Freescale BOOKE >> > > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of >> > > > > description in the Kconfig field, which makes it impossible >> > > > > to support L2Cache-Sram driver. Add a description to make it >> > > > > configurable. >> > > > > >> > > > > Signed-off-by: wangwenhu >> > > > >> > > > The intent was that drivers using the SRAM API would select the >> > > > symbol. What >> > > > is the use case for selecting it manually? >> > > > >> > > >> > > With a repository of multiple products(meaning different defconfigs) and >> > > multiple >> > > developers, the Kconfigs of the Kernel Source Tree change frequently. So >> > > the >> > > "make menuconfig" >> > > process is needed for defconfigs' re-generating or updating for the >> > > complexity of dependencies >> > > between different features defined in the Kconfigs. >> > >> > That doesn't answer my question of how the SRAM code would be useful other >> > than to some other driver that uses the API (which would use >> > "select"). There >> > is no userspace API. You could use the kernel command line to configure >> > the >> > SRAM but you need to get the address of it for it to be useful. >> > >> >> Like you've asked below, via /dev/mem or direct calling within the Kernel. >> And they are not submitted yes, under development. > >If they are calling within the kernel, then whatever driver that is should >select FSL_85XX_CACHE_SRAM. Directly accessing /dev/mem without any way for >the kernel to advertise where it is or which parts of SRAM are available for >use sounds like a bad idea. > Yes, definitely. So like we enable the moulde which should selet FSL_85XX_CACHE_SRAM to build vmlinux, FSL_85XX_CACHE_SRAM could not be seleted because of the Kconfig definition problem which I am trying to fix now. So would you please merge the patch for the convenience of later works depending on the driver. Wenhu >-Scott > >
Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
On Mon, 2020-03-02 at 12:42 +0800, 王文虎 wrote: > 发件人：Scott Wood > 发送日期：2020-03-01 07:12:58 > 收件人："王文虎" > 抄送人：wangwenhu ,Kumar Gala ,B > enjamin Herrenschmidt ,Paul Mackerras < > pau...@samba.org>,Michael Ellerman , > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, > triv...@kernel.org,Rai Harninder > 主题：Re: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On > Tue, 2020-01-21 at 14:38 +0800, 王文虎 wrote: > > > 发件人：Scott Wood > > > 发送日期：2020-01-21 13:49:59 > > > 收件人："王文虎" > > > 抄送人：wangwenhu ,Kumar Gala < > > > ga...@kernel.crashing.org>,B > > > enjamin Herrenschmidt ,Paul Mackerras < > > > pau...@samba.org>,Michael Ellerman , > > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, > > > triv...@kernel.org,Rai Harninder > > > 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On > > > Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: > > > > > From: Scott Wood > > > > > Date: 2020-01-21 11:25:25 > > > > > To: wangwenhu ,Kumar Gala < > > > > > ga...@kernel.crashing.org>, > > > > > Benjamin Herrenschmidt ,Paul Mackerras < > > > > > pau...@samba.org>,Michael Ellerman , > > > > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org > > > > > Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < > > > > > harninder@nxp.com> > > > > > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM > > > > > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: > > > > > > > From: wangwenhu > > > > > > > > > > > > > > When generating .config file with menuconfig on Freescale BOOKE > > > > > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of > > > > > > > description in the Kconfig field, which makes it impossible > > > > > > > to support L2Cache-Sram driver. Add a description to make it > > > > > > > configurable. > > > > > > > > > > > > > > Signed-off-by: wangwenhu > > > > > > > > > > > > The intent was that drivers using the SRAM API would select the > > > > > > symbol. What > > > > > > is the use case for selecting it manually? > > > > > > > > > > > > > > > > With a repository of multiple products(meaning different defconfigs) > > > > > and > > > > > multiple > > > > > developers, the Kconfigs of the Kernel Source Tree change > > > > > frequently. So > > > > > the > > > > > "make menuconfig" > > > > > process is needed for defconfigs' re-generating or updating for the > > > > > complexity of dependencies > > > > > between different features defined in the Kconfigs. > > > > > > > > That doesn't answer my question of how the SRAM code would be useful > > > > other > > > > than to some other driver that uses the API (which would use > > > > "select"). There > > > > is no userspace API. You could use the kernel command line to > > > > configure > > > > the > > > > SRAM but you need to get the address of it for it to be useful. > > > > > > > > > > Like you've asked below, via /dev/mem or direct calling within the > > > Kernel. > > > And they are not submitted yes, under development. > > > > If they are calling within the kernel, then whatever driver that is should > > select FSL_85XX_CACHE_SRAM. Directly accessing /dev/mem without any way > > for > > the kernel to advertise where it is or which parts of SRAM are available > > for > > use sounds like a bad idea. > > > > Yes, definitely. So like we enable the moulde which should selet > FSL_85XX_CACHE_SRAM to build vmlinux, FSL_85XX_CACHE_SRAM > could not be seleted because of the Kconfig definition problem > which I am trying to fix now. So would you please merge the patch > for the convenience of later works depending on the driver. Sorry, I don't think it's something that should be enabled by itself with nothing using the allocators. Suppose we took this patch, and people enabled it and accessed it via /dev/mem. Then suppose a driver is patched to allocate some sram and use it. They'd be stepping on each others' toes undetected. If you want to expose it to userspace, add code that allocates some or all of the sram and make it something userspace can mmap. Or, if nothing's going to use them, remove the allocators and export the entire thing to userspace (again via an sram-specific mappable rather than /dev/mem). -Scott
Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
发件人：Scott Wood 发送日期：2020-03-02 16:58:52 收件人："王文虎" 抄送人：wangwenhu ,Kumar Gala ,Benjamin Herrenschmidt ,Paul Mackerras ,Michael Ellerman ,linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org,triv...@kernel.org,Rai Harninder 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On Mon, 2020-03-02 at 12:42 +0800, 王文虎 wrote: >> 发件人：Scott Wood >> 发送日期：2020-03-01 07:12:58 >> 收件人："王文虎" >> 抄送人：wangwenhu ,Kumar Gala ,B >> enjamin Herrenschmidt ,Paul Mackerras < >> pau...@samba.org>,Michael Ellerman , >> linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, >> triv...@kernel.org,Rai Harninder >> 主题：Re: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On >> Tue, 2020-01-21 at 14:38 +0800, 王文虎 wrote: >> > > 发件人：Scott Wood >> > > 发送日期：2020-01-21 13:49:59 >> > > 收件人："王文虎" >> > > 抄送人：wangwenhu ,Kumar Gala < >> > > ga...@kernel.crashing.org>,B >> > > enjamin Herrenschmidt ,Paul Mackerras < >> > > pau...@samba.org>,Michael Ellerman , >> > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, >> > > triv...@kernel.org,Rai Harninder >> > > 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On >> > > Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: >> > > > > From: Scott Wood >> > > > > Date: 2020-01-21 11:25:25 >> > > > > To: wangwenhu ,Kumar Gala < >> > > > > ga...@kernel.crashing.org>, >> > > > > Benjamin Herrenschmidt ,Paul Mackerras < >> > > > > pau...@samba.org>,Michael Ellerman , >> > > > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org >> > > > > Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < >> > > > > harninder@nxp.com> >> > > > > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM >> > > > > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: >> > > > > > > From: wangwenhu >> > > > > > > >> > > > > > > When generating .config file with menuconfig on Freescale BOOKE >> > > > > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of >> > > > > > > description in the Kconfig field, which makes it impossible >> > > > > > > to support L2Cache-Sram driver. Add a description to make it >> > > > > > > configurable. >> > > > > > > >> > > > > > > Signed-off-by: wangwenhu >> > > > > > >> > > > > > The intent was that drivers using the SRAM API would select the >> > > > > > symbol. What >> > > > > > is the use case for selecting it manually? >> > > > > > >> > > > > >> > > > > With a repository of multiple products(meaning different defconfigs) >> > > > > and >> > > > > multiple >> > > > > developers, the Kconfigs of the Kernel Source Tree change >> > > > > frequently. So >> > > > > the >> > > > > "make menuconfig" >> > > > > process is needed for defconfigs' re-generating or updating for the >> > > > > complexity of dependencies >> > > > > between different features defined in the Kconfigs. >> > > > >> > > > That doesn't answer my question of how the SRAM code would be useful >> > > > other >> > > > than to some other driver that uses the API (which would use >> > > > "select"). There >> > > > is no userspace API. You could use the kernel command line to >> > > > configure >> > > > the >> > > > SRAM but you need to get the address of it for it to be useful. >> > > > >> > > >> > > Like you've asked below, via /dev/mem or direct calling within the >> > > Kernel. >> > > And they are not submitted yes, under development. >> > >> > If they are calling within the kernel, then whatever driver that is should >> > select FSL_85XX_CACHE_SRAM. Directly accessing /dev/mem without any way >> > for >> > the kernel to advertise where it is or which parts of SRAM are available >> > for >> > use sounds like a bad idea. >>
Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: > From: wangwenhu > > When generating .config file with menuconfig on Freescale BOOKE > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of > description in the Kconfig field, which makes it impossible > to support L2Cache-Sram driver. Add a description to make it > configurable. > > Signed-off-by: wangwenhu The intent was that drivers using the SRAM API would select the symbol. What is the use case for selecting it manually? Since this code was added almost ten years ago and there are still no (in- tree?) users of the API, we should just remove the sram code (unless this prods someone to submit such a user very soon). -Scott
Re:[PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
From: Scott Wood Date: 2020-01-21 11:25:25 To: wangwenhu ,Kumar Gala ,Benjamin Herrenschmidt ,Paul Mackerras ,Michael Ellerman ,linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: >> From: wangwenhu >> >> When generating .config file with menuconfig on Freescale BOOKE >> SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of >> description in the Kconfig field, which makes it impossible >> to support L2Cache-Sram driver. Add a description to make it >> configurable. >> >> Signed-off-by: wangwenhu > >The intent was that drivers using the SRAM API would select the symbol. What >is the use case for selecting it manually? > With a repository of multiple products(meaning different defconfigs) and multiple developers, the Kconfigs of the Kernel Source Tree change frequently. So the "make menuconfig" process is needed for defconfigs' re-generating or updating for the complexity of dependencies between different features defined in the Kconfigs. >Since this code was added almost ten years ago and there are still no (in- >tree?) users of the API, we should just remove the sram code (unless this >prods someone to submit such a user very soon). > Yes, pretty long a time. But we DO really use the API now for PPCE500/Freescale SoC. Like sometimes we need to reset the whole RAM, then the L2-Cache would be used as SRAM for backup using. Since it is useful for us now, a re-consideration is recommanded. >-Scott > > -- Wenhu vivo
Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
On Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: > From: Scott Wood > Date: 2020-01-21 11:25:25 > To: wangwenhu ,Kumar Gala , > Benjamin Herrenschmidt ,Paul Mackerras < > pau...@samba.org>,Michael Ellerman , > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org > Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < > harninder....@nxp.com> > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: > > > From: wangwenhu > > > > > > When generating .config file with menuconfig on Freescale BOOKE > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of > > > description in the Kconfig field, which makes it impossible > > > to support L2Cache-Sram driver. Add a description to make it > > > configurable. > > > > > > Signed-off-by: wangwenhu > > > > The intent was that drivers using the SRAM API would select the > > symbol. What > > is the use case for selecting it manually? > > > > With a repository of multiple products(meaning different defconfigs) and > multiple > developers, the Kconfigs of the Kernel Source Tree change frequently. So the > "make menuconfig" > process is needed for defconfigs' re-generating or updating for the > complexity of dependencies > between different features defined in the Kconfigs. That doesn't answer my question of how the SRAM code would be useful other than to some other driver that uses the API (which would use "select"). There is no userspace API. You could use the kernel command line to configure the SRAM but you need to get the address of it for it to be useful. > > Since this code was added almost ten years ago and there are still no (in- > > tree?) users of the API, we should just remove the sram code (unless this > > prods someone to submit such a user very soon). > > > > Yes, pretty long a time. But we DO really use the API now for > PPCE500/Freescale SoC. I do not see any users in the kernel tree. Are you talking about out-of-tree code, or something that you've submitted or will submit soon? Or are you accessing it via /dev/mem? > Like sometimes we need to reset the whole RAM, then the L2-Cache would be > used as > SRAM for backup using. Since it is useful for us now, a re-consideration is > recommanded. Where is the code that would do this? -Scott >
Re:Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
发件人：Scott Wood 发送日期：2020-01-21 13:49:59 收件人："王文虎" 抄送人：wangwenhu ,Kumar Gala ,Benjamin Herrenschmidt ,Paul Mackerras ,Michael Ellerman ,linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org,triv...@kernel.org,Rai Harninder 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: >> From: Scott Wood >> Date: 2020-01-21 11:25:25 >> To: wangwenhu ,Kumar Gala , >> Benjamin Herrenschmidt ,Paul Mackerras < >> pau...@samba.org>,Michael Ellerman , >> linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org >> Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < >> harninder@nxp.com> >> Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM >> configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: >> > > From: wangwenhu >> > > >> > > When generating .config file with menuconfig on Freescale BOOKE >> > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of >> > > description in the Kconfig field, which makes it impossible >> > > to support L2Cache-Sram driver. Add a description to make it >> > > configurable. >> > > >> > > Signed-off-by: wangwenhu >> > >> > The intent was that drivers using the SRAM API would select the >> > symbol. What >> > is the use case for selecting it manually? >> > >> >> With a repository of multiple products(meaning different defconfigs) and >> multiple >> developers, the Kconfigs of the Kernel Source Tree change frequently. So the >> "make menuconfig" >> process is needed for defconfigs' re-generating or updating for the >> complexity of dependencies >> between different features defined in the Kconfigs. > >That doesn't answer my question of how the SRAM code would be useful other >than to some other driver that uses the API (which would use "select"). There >is no userspace API. You could use the kernel command line to configure the >SRAM but you need to get the address of it for it to be useful. > Like you've asked below, via /dev/mem or direct calling within the Kernel. And they are not submitted yes, under development. >> > Since this code was added almost ten years ago and there are still no (in- >> > tree?) users of the API, we should just remove the sram code (unless this >> > prods someone to submit such a user very soon). >> > >> >> Yes, pretty long a time. But we DO really use the API now for >> PPCE500/Freescale SoC. > >I do not see any users in the kernel tree. Are you talking about out-of-tree >code, or something that you've submitted or will submit soon? Or are you >accessing it via /dev/mem? > Both, but not submitted yet, and partly under development. >> Like sometimes we need to reset the whole RAM, then the L2-Cache would be >> used as >> SRAM for backup using. Since it is useful for us now, a re-consideration is >> recommanded. > >Where is the code that would do this? > Currently under development, and not submitted yet. >-Scott >> > Wenhu
Re: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable
On Tue, 2020-01-21 at 14:38 +0800, 王文虎 wrote: > 发件人：Scott Wood > 发送日期：2020-01-21 13:49:59 > 收件人："王文虎" > 抄送人：wangwenhu ,Kumar Gala ,B > enjamin Herrenschmidt ,Paul Mackerras < > pau...@samba.org>,Michael Ellerman , > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org, > triv...@kernel.org,Rai Harninder > 主题：Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM configurable>On > Tue, 2020-01-21 at 13:20 +0800, 王文虎 wrote: > > > From: Scott Wood > > > Date: 2020-01-21 11:25:25 > > > To: wangwenhu ,Kumar Gala < > > > ga...@kernel.crashing.org>, > > > Benjamin Herrenschmidt ,Paul Mackerras < > > > pau...@samba.org>,Michael Ellerman , > > > linuxppc-dev@lists.ozlabs.org,linux-ker...@vger.kernel.org > > > Cc: triv...@kernel.org,wenhu.w...@vivo.com,Rai Harninder < > > > harninder@nxp.com> > > > Subject: Re: [PATCH] powerpc/Kconfig: Make FSL_85XX_CACHE_SRAM > > > configurable>On Mon, 2020-01-20 at 06:43 -0800, wangwenhu wrote: > > > > > From: wangwenhu > > > > > > > > > > When generating .config file with menuconfig on Freescale BOOKE > > > > > SOC, FSL_85XX_CACHE_SRAM is not configurable for the lack of > > > > > description in the Kconfig field, which makes it impossible > > > > > to support L2Cache-Sram driver. Add a description to make it > > > > > configurable. > > > > > > > > > > Signed-off-by: wangwenhu > > > > > > > > The intent was that drivers using the SRAM API would select the > > > > symbol. What > > > > is the use case for selecting it manually? > > > > > > > > > > With a repository of multiple products(meaning different defconfigs) and > > > multiple > > > developers, the Kconfigs of the Kernel Source Tree change frequently. So > > > the > > > "make menuconfig" > > > process is needed for defconfigs' re-generating or updating for the > > > complexity of dependencies > > > between different features defined in the Kconfigs. > > > > That doesn't answer my question of how the SRAM code would be useful other > > than to some other driver that uses the API (which would use > > "select"). There > > is no userspace API. You could use the kernel command line to configure > > the > > SRAM but you need to get the address of it for it to be useful. > > > > Like you've asked below, via /dev/mem or direct calling within the Kernel. > And they are not submitted yes, under development. If they are calling within the kernel, then whatever driver that is should select FSL_85XX_CACHE_SRAM. Directly accessing /dev/mem without any way for the kernel to advertise where it is or which parts of SRAM are available for use sounds like a bad idea. -Scott
