From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cdafJ-0007F1-DZ for barebox@lists.infradead.org; Tue, 14 Feb 2017 10:48:59 +0000 Date: Tue, 14 Feb 2017 11:48:33 +0100 From: Sascha Hauer Message-ID: <20170214104833.k5oubzucxb3o67rf@pengutronix.de> References: <4bcf7de3-5ced-3575-9495-c1f4f20ce60c@phytec.de> <20170213192247.gjld5b33genwav2a@pengutronix.de> <6ff1f0fb-5847-e927-0602-a61c35a58e5b@phytec.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6ff1f0fb-5847-e927-0602-a61c35a58e5b@phytec.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: barebox PBL question To: Wadim Egorov Cc: "barebox@lists.infradead.org" On Tue, Feb 14, 2017 at 10:54:49AM +0100, Wadim Egorov wrote: > > On 13.02.2017 20:22, Sascha Hauer wrote: > > On Mon, Feb 13, 2017 at 04:13:48PM +0100, Wadim Egorov wrote: > >> Hi, > >> > >> I would like to add SPL support for the RK3288 SoC to barebox. But I am > >> facing > >> a few problems. > >> > >> The maximum size of the SPL image which the ROM code will read is 32KB. > >> I was thinking to use the PBL feature for the SPL part. But using the > >> the pbl code (with decompression) seems to be not a good idea, because > >> it's size > >> is already about 30K. I think this is an overhead. > > In a test build here the pbl code is 6KiB. The rest is the devicetree > > included in the binary (which I disabled in the test build). The dtb can > > be compressed which should give you enough space even in 32KiB. > OK, I think I checked the wrong file size. pblb is the bare binary file > > > > >> But now I wonder how to generate two different images with a single build. > >> A SPL image, which should not exceed 32K and a barebox. > >> > >> I have problems to fully understand the PBL mechanism. > >> Why are the builds always adding the barebox.bin images to the PBL part? > > The idea is to create an image that contains the PBL and attached to it > > the compressed barebox image. If your ROM only allows a certain image > > size then make sure the PBL is small enough and tell the ROM to only > > load the PBL part of the image. Ideally the PBL then detects from where > > the PBL is loaded (by reading back the bootsource the SoC provides) and > > reads the rest of the image into SDRAM (or, for sake of simplicity, the > > whole image inculding PBL again) > ty for clarification > > > > >> Here is an example, cat .zbarebox.cmd > >> > >> ld -EL -Map arch/arm/pbl/zbarebox.map --gc-sections -static -o > >> arch/arm/pbl/zbarebox -e pbl_start -T arch/arm/pbl/zbarebox.lds > >> --start-group common/built-in-pbl.o [...] arch/arm/pbl/piggy.shipped.o > >> --end-group > >> > >> piggy.shipped.o is barebox.bin, which is added in piggy.shipped.S: > >> > >> .incbin "arch/arm/pbl/piggy.shipped" > > You should use PBL_MULTI_IMAGES instead. In fact, the existing Rockchip > > port already does this. > > > > I think your entry function should look something like: > > > > ENTRY_FUNCTION(start_rk3288_phycore_som, r0, r1, r2) > > { > > arm_cpu_lowlevel_init(); > > > > if (inside_sdram(get_pc())) > > barebox_arm_entry(0x0, SZ_1G, fdt); > > > > rk3288_phycore_setup_sdram(); > > > > jump_back_to_rom(); > > } > > > > I don't know how jump_back_to_rom() should be implemented. Do you have > > to return from the entry function to the ROM or does the ROM provide some API > > which can be used to chainload the rest of the image? > > No, there is no API in the ROM. > In u-boot the spl will return to bootrom in board_init_f(), then bootrom > loads u-boot binary. The ENTRY_FUNCTION macro is not prepared for returning to the caller. You'll have to replace it with something like: void __section(.text_head_entry_start_rk3288_phycore_som) start_start_imx6q_sabrelite(uint32_t r0, uint32_t r1, uint32_t r2) This makes sure the link register is preserved and is jumped to at the end of the function. You could also send me some hardware, I could provide some better help then. I know this early bringup can be tricky ;) Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox