From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailrelay-egress4.pub.mailoutpod2-cph3.one.com (mailrelay-egress4.pub.mailoutpod2-cph3.one.com [46.30.211.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D60D43939A4 for ; Sun, 30 Aug 2026 18:19:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.30.211.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788113975; cv=none; b=ds6uOEfHULEMvg+ymUkiyarJMcVymVNlLpar0eoH0OVi5Vi3da46Qpe78I1Y2d92ZTv+xEUe8atbhWHxYGf1D1Mf/19WIdFkhZliKa3z9LOFbnj24SJa4mAASid0lpV4mcmgIF6ReTJQIGTn0QPncDmSnmJxFbSyXuPg2o3e7hc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788113975; c=relaxed/simple; bh=wE3c/wmM5OzRIyWKsSpWFgA3iTd2icZ/cI2iWtiScWs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PvMHzIAj0BtMBMM8/MLAf6wK3DWaccgBzWU0/cidyozWjBAHiUdAGpIaLUL7ac6fMYmyrzNH4US6pLuOfKVnzsgA1gP22/TsJkd3nKV50AieuUMjeNeCuGykoHhxcYC4BCh0f5ZZjpR5l0MG2/fCKHQ7JioYIClZWob7sReNq8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ravnborg.org; spf=none smtp.mailfrom=ravnborg.org; dkim=pass (2048-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b=Qd5Q983q; dkim=permerror (0-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b=PpfhJhep; arc=none smtp.client-ip=46.30.211.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ravnborg.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ravnborg.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b="Qd5Q983q"; dkim=permerror (0-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b="PpfhJhep" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1788113968; x=1788718768; d=ravnborg.org; s=rsa1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=ptquxSg1allIZ9AUJUQ7fX24xqplOgszxhi7rZ2eIpw=; b=Qd5Q983qtxugD6eo/z3xhgrrfITprm/vss9cIJm+Z5aiOzqS852sDwGW5iRs+CLFko6kt/+khmCdd SlZKM3Q8KdY1Y9vvW41bjr7+j+6N9CGbNMnytzmXq4mgEpK7+wrdakeivme92mledbmtU95EOUxYPd h0oMB44oQ6tWR7IabhuXon5PEgc8phAq4qfX9uDyunCPGsD+zccKWI+SDADq7sF9nS76lk1XTjr9dq imKsygdAwvKvk2ArVhLq372AHm3cN1+2fM5LSOmN5Fd/FipG3bjNC51u/IvV1rp51aoQ7lXxqn5tcd zjhm1rdnk3p0A4LKSVNvsgC2fXCJ1Bw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; t=1788113968; x=1788718768; d=ravnborg.org; s=ed1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=ptquxSg1allIZ9AUJUQ7fX24xqplOgszxhi7rZ2eIpw=; b=PpfhJhepbUTWl75eDa5188wbS5nNhEgaqxdF5qljFxVC9EG+Co6P3uS0T+7IVKO5rca9rhg4kbgaP fXAGxWxBA== X-HalOne-ID: 54882306-a49f-11f1-b5c3-f14abb5dfc6c Received: from ravnborg.org (unknown [2a00:fd01:81e9:6100:f5ac:d3d2:8b9f:e425]) by mailrelay1.pub.mailoutpod2-cph3.one.com (Halon) with ESMTPSA id 54882306-a49f-11f1-b5c3-f14abb5dfc6c; Sun, 30 Aug 2026 18:19:27 +0000 (UTC) Date: Sun, 30 Aug 2026 20:19:26 +0200 From: Sam Ravnborg To: Magnus Lindholm Cc: sparclinux@vger.kernel.org, davem@davemloft.net, andreas@gaisler.com, linux-kernel@vger.kernel.org, glaubitz@physik.fu-berlin.de Subject: Re: [PATCH v2 5/6] sparc32: move early memory setup to setup_arch Message-ID: <20260830181926.GB173328@ravnborg.org> References: <20260830120742.20950-1-linmag7@gmail.com> <20260830120742.20950-6-linmag7@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260830120742.20950-6-linmag7@gmail.com> On Sun, Aug 30, 2026 at 02:06:44PM +0200, Magnus Lindholm wrote: > Move the early memory configuration out of SRMMU paging setup and next to > the rest of setup_arch(). Derive the PFN limits from memblock, reserve the > kernel and initrd there, and retain mem= support with > memblock_enforce_memory_limit(). > > Use for_each_mem_pfn_range() to find the lowmem boundary and replace > last_valid_pfn with the standard max_low_pfn variable. This tightens > LEON's _pfn_valid() upper bound from all RAM to the lowmem limit, with no > functional change because LEON does not use highmem. > > When PAGE_OFFSET maps a relocated kernel, remove memory below phys_base > from memblock because it cannot be reached through the linear map. This > replaces the equivalent trimming of sp_banks. We have several >> PAGE_SHIFT and << PAGE_SHIFT. It would be more readable to use the corresponding: PHYS_PFN() and PFN_PHYS(). Left a few comments in the following. Sam > > Suggested-by: Sam Ravnborg > Signed-off-by: Magnus Lindholm > --- > arch/sparc/include/asm/leon.h | 2 +- > arch/sparc/include/asm/pgtable_32.h | 3 +- > arch/sparc/include/asm/pgtsrmmu.h | 2 +- > arch/sparc/kernel/setup_32.c | 115 +++++++++++++----------- > arch/sparc/mm/init_32.c | 132 +--------------------------- > arch/sparc/mm/srmmu.c | 6 -- > 6 files changed, 69 insertions(+), 191 deletions(-) > > diff --git a/arch/sparc/include/asm/leon.h b/arch/sparc/include/asm/leon.h > index 053a24b67aed..815131c77ed7 100644 > --- a/arch/sparc/include/asm/leon.h > +++ b/arch/sparc/include/asm/leon.h > @@ -251,7 +251,7 @@ extern int leon_ipi_irq; > > /* macros used in leon_mm.c */ > #define PFN(x) ((x) >> PAGE_SHIFT) A cleanup for another day is replacing PFN() with the standard PFN_DOWN(). > -#define _pfn_valid(pfn) ((pfn < last_valid_pfn) && (pfn >= PFN(phys_base))) > +#define _pfn_valid(pfn) ((pfn < max_low_pfn) && (pfn >= PFN(phys_base))) > #define _SRMMU_PTE_PMASK_LEON 0xffffffff > > /* > diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h > index f89b1250661d..91a6032cf6a2 100644 > --- a/arch/sparc/include/asm/pgtable_32.h > +++ b/arch/sparc/include/asm/pgtable_32.h > @@ -37,8 +37,7 @@ struct vm_area_struct; > struct page; > > void load_mmu(void); > -unsigned long calc_highpages(void); > -unsigned long __init bootmem_init(unsigned long *pages_avail); > +void __init find_ramdisk(unsigned long end_of_phys_memory); > > #define pte_ERROR(e) __builtin_trap() > #define pmd_ERROR(e) __builtin_trap() > diff --git a/arch/sparc/include/asm/pgtsrmmu.h b/arch/sparc/include/asm/pgtsrmmu.h > index a265822a475e..9ce7558113f8 100644 > --- a/arch/sparc/include/asm/pgtsrmmu.h > +++ b/arch/sparc/include/asm/pgtsrmmu.h > @@ -98,7 +98,7 @@ > restore %g0, %g0, %g0; > > #ifndef __ASSEMBLER__ > -extern unsigned long last_valid_pfn; > +extern unsigned long max_low_pfn; This is already declared in memblock.h: $ git grep max_low_pfn include/linux/memblock.h:extern unsigned long max_low_pfn; > > /* This makes sense. Honest it does - Anton */ > /* XXX Yes but it's ugly as sin. FIXME. -KMW */ > diff --git a/arch/sparc/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c > index 795714959da6..c3c3274e55af 100644 > --- a/arch/sparc/kernel/setup_32.c > +++ b/arch/sparc/kernel/setup_32.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -254,28 +255,74 @@ static __init void leon_patch(void) > > struct tt_entry *sparc_ttable; > > -/* Drop RAM below the kernel; the linear map runs upward from phys_base > - * and cannot reach it. > - */ > -static void __init trim_sp_banks_below(unsigned long base) > +unsigned long phys_base; > +EXPORT_SYMBOL(phys_base); > + > +unsigned long pfn_base; > +EXPORT_SYMBOL(pfn_base); It is likely just me, but I get a bit confused over all the names here. pfn_phys_base had been easier for me, so I knew this was the PFN of phys_base. This is unrelated to this patch, just a comment while trying to page in how this code works. > + > +unsigned long highend_pfn; > + > +static unsigned long __init calc_max_low_pfn(void) > { > - int i, j = 0; > + unsigned long limit = pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT); > + unsigned long start_pfn, end_pfn; > + unsigned long last_pfn = 0; > + int i; > + > + for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, > + NULL) { No need to break this up, we are not above 80 columns. > + if (start_pfn >= limit) { > + if (last_pfn < limit) > + limit = last_pfn; > + break; > + } > > - for (i = 0; sp_banks[i].num_bytes != 0; i++) { > - unsigned long start = sp_banks[i].base_addr; > - unsigned long end = start + sp_banks[i].num_bytes; > + last_pfn = end_pfn; > + } > > - if (end <= base) > - continue; /* wholly below - drop it */ > - if (start < base) > - start = base; /* straddles - trim the front */ > + return limit; > +} > > - sp_banks[j].base_addr = start; > - sp_banks[j].num_bytes = end - start; > - j++; > +static void __init setup_memory(void) > +{ > + unsigned long ram_base = memblock_start_of_DRAM(); > + unsigned long real_base = __get_phys(PAGE_OFFSET); > + unsigned long size; > + > + memblock_set_bottom_up(true); > + memblock_allow_resize(); > + > + phys_base = ram_base; > + if (real_base && real_base != phys_base) { > + prom_printf("phys_base: RAM starts 0x%x but kernel is at 0x%x\n", > + (unsigned int)phys_base, (unsigned int)real_base); > + phys_base = real_base; > + memblock_remove(0, phys_base); > + prom_printf("phys_base: adopted 0x%x, RAM below it dropped\n", > + (unsigned int)phys_base); > } > - sp_banks[j].base_addr = 0; > - sp_banks[j].num_bytes = 0; > + > + if (cmdline_memory_size) > + memblock_enforce_memory_limit(cmdline_memory_size); > + > + min_low_pfn = PFN_DOWN(memblock_start_of_DRAM()); > + pfn_base = phys_base >> PAGE_SHIFT; > + max_low_pfn = PFN_DOWN(memblock_end_of_DRAM()); > + highend_pfn = max_low_pfn; highend_pfn is only used to set max_zone_pfn[ZONE_HIGHMEM]. It would be simpler to just use max_low_pfn and get rid of highend_pfn. This part should also set max_pfn. > + > + if (max_low_pfn > pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT)) > + max_low_pfn = calc_max_low_pfn(); Set max_pfn here. > + > + find_ramdisk(memblock_end_of_DRAM()); > + > + /* Reserve the kernel text/data/bss. */ > + size = __pa(PAGE_ALIGN((unsigned long)&_end)) - phys_base; > + memblock_reserve(phys_base, size); > + memblock_add(phys_base, size); > + > + /* Only allow low memory to be allocated by memblock. */ > + memblock_set_current_limit(PFN_PHYS(max_low_pfn)); > } > > /* Called from head_32.S - before we have setup anything > @@ -306,9 +353,6 @@ void __init sparc32_start_kernel(struct linux_romvec *rp) > > void __init setup_arch(char **cmdline_p) > { > - int i; > - unsigned long highest_paddr; > - > sparc_ttable = &trapbase[0]; > > /* Initialize PROM console and command line. */ > @@ -343,36 +387,7 @@ void __init setup_arch(char **cmdline_p) > > idprom_init(); > load_mmu(); > - > - phys_base = 0xffffffffUL; > - highest_paddr = 0UL; > - for (i = 0; sp_banks[i].num_bytes != 0; i++) { > - unsigned long top; > - > - if (sp_banks[i].base_addr < phys_base) > - phys_base = sp_banks[i].base_addr; > - top = sp_banks[i].base_addr + > - sp_banks[i].num_bytes; > - if (highest_paddr < top) > - highest_paddr = top; > - } > - > - /* phys_base must describe what PAGE_OFFSET maps to, not where RAM starts. */ > - { > - unsigned long real_base = __get_phys(PAGE_OFFSET); > - > - if (real_base && real_base != phys_base) { > - prom_printf("phys_base: RAM starts 0x%x but kernel is at 0x%x\n", > - (unsigned int)phys_base, > - (unsigned int)real_base); > - phys_base = real_base; > - trim_sp_banks_below(phys_base); > - prom_printf("phys_base: adopted 0x%x, RAM below it dropped\n", > - (unsigned int)phys_base); > - } > - } > - > - pfn_base = phys_base >> PAGE_SHIFT; > + setup_memory(); > > if (!root_flags) > root_mountflags &= ~MS_RDONLY; > diff --git a/arch/sparc/mm/init_32.c b/arch/sparc/mm/init_32.c > index 6880d9cb30a5..ac4462f1cf76 100644 > --- a/arch/sparc/mm/init_32.c > +++ b/arch/sparc/mm/init_32.c > @@ -35,66 +35,13 @@ > > #include "mm_32.h" > > -unsigned long phys_base; > -EXPORT_SYMBOL(phys_base); > - > -unsigned long pfn_base; > -EXPORT_SYMBOL(pfn_base); > - > struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS+1]; > > /* Initial ramdisk setup */ > extern unsigned int sparc_ramdisk_image; > extern unsigned int sparc_ramdisk_size; > > -unsigned long highstart_pfn, highend_pfn; > - > -unsigned long last_valid_pfn; > - > -unsigned long calc_highpages(void) > -{ > - int i; > - int nr = 0; > - > - for (i = 0; sp_banks[i].num_bytes != 0; i++) { > - unsigned long start_pfn = sp_banks[i].base_addr >> PAGE_SHIFT; > - unsigned long end_pfn = (sp_banks[i].base_addr + sp_banks[i].num_bytes) >> PAGE_SHIFT; > - > - if (end_pfn <= max_low_pfn) > - continue; > - > - if (start_pfn < max_low_pfn) > - start_pfn = max_low_pfn; > - > - nr += end_pfn - start_pfn; > - } > - > - return nr; > -} > - > -static unsigned long calc_max_low_pfn(void) > -{ > - int i; > - unsigned long tmp = pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT); > - unsigned long curr_pfn, last_pfn; > - > - last_pfn = (sp_banks[0].base_addr + sp_banks[0].num_bytes) >> PAGE_SHIFT; > - for (i = 1; sp_banks[i].num_bytes != 0; i++) { > - curr_pfn = sp_banks[i].base_addr >> PAGE_SHIFT; > - > - if (curr_pfn >= tmp) { > - if (last_pfn < tmp) > - tmp = last_pfn; > - break; > - } > - > - last_pfn = (sp_banks[i].base_addr + sp_banks[i].num_bytes) >> PAGE_SHIFT; > - } > - > - return tmp; > -} > - > -static void __init find_ramdisk(unsigned long end_of_phys_memory) > +void __init find_ramdisk(unsigned long end_of_phys_memory) > { > #ifdef CONFIG_BLK_DEV_INITRD > unsigned long size; > @@ -124,83 +71,6 @@ static void __init find_ramdisk(unsigned long end_of_phys_memory) > #endif > } > > -unsigned long __init bootmem_init(unsigned long *pages_avail) > -{ > - unsigned long start_pfn, bytes_avail, size; > - unsigned long end_of_phys_memory = 0; > - unsigned long high_pages = 0; > - int i; > - > - memblock_set_bottom_up(true); > - memblock_allow_resize(); > - > - bytes_avail = 0UL; > - for (i = 0; sp_banks[i].num_bytes != 0; i++) { > - end_of_phys_memory = sp_banks[i].base_addr + > - sp_banks[i].num_bytes; > - bytes_avail += sp_banks[i].num_bytes; > - if (cmdline_memory_size) { > - if (bytes_avail > cmdline_memory_size) { > - unsigned long slack = bytes_avail - cmdline_memory_size; > - > - bytes_avail -= slack; > - end_of_phys_memory -= slack; > - > - sp_banks[i].num_bytes -= slack; > - if (sp_banks[i].num_bytes == 0) { > - sp_banks[i].base_addr = 0xdeadbeef; > - } else { > - memblock_add(sp_banks[i].base_addr, > - sp_banks[i].num_bytes); > - sp_banks[i+1].num_bytes = 0; > - sp_banks[i+1].base_addr = 0xdeadbeef; > - } > - break; > - } > - } > - memblock_add(sp_banks[i].base_addr, sp_banks[i].num_bytes); > - } > - > - if (cmdline_memory_size) > - memblock_enforce_memory_limit(cmdline_memory_size); > - > - /* Start with page aligned address of last symbol in kernel > - * image. > - */ > - start_pfn = (unsigned long)__pa(PAGE_ALIGN((unsigned long) &_end)); > - > - /* Now shift down to get the real physical page frame number. */ > - start_pfn >>= PAGE_SHIFT; > - > - max_pfn = end_of_phys_memory >> PAGE_SHIFT; > - > - max_low_pfn = max_pfn; > - highstart_pfn = highend_pfn = max_pfn; > - > - if (max_low_pfn > pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT)) { > - highstart_pfn = pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT); > - max_low_pfn = calc_max_low_pfn(); > - high_pages = calc_highpages(); > - printk(KERN_NOTICE "%ldMB HIGHMEM available.\n", > - high_pages >> (20 - PAGE_SHIFT)); > - } All the above are not needed as the kernel already print HIGHMEM, and this patch removes it - good. Maybe tell so in the commit message? This could also go in before to keep this not-so-readable patch smaller. > - > - find_ramdisk(end_of_phys_memory); > - > - /* Reserve the kernel text/data/bss. */ > - size = (start_pfn << PAGE_SHIFT) - phys_base; > - memblock_reserve(phys_base, size); > - memblock_add(phys_base, size); > - > - size = memblock_phys_mem_size() - memblock_reserved_size(); > - *pages_avail = (size >> PAGE_SHIFT) - high_pages; > - > - /* Only allow low memory to be allocated via memblock allocation */ > - memblock_set_current_limit(max_low_pfn << PAGE_SHIFT); > - > - return max_pfn; > -} > - > /* > * paging_init() sets up the page tables: We call the MMU specific > * init routine based upon the Sun model type on the Sparc. > diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c > index 3029527a5a9f..cf66a108b411 100644 > --- a/arch/sparc/mm/srmmu.c > +++ b/arch/sparc/mm/srmmu.c > @@ -59,8 +59,6 @@ int vac_line_size; > > extern struct resource sparc_iomap; > > -extern unsigned long last_valid_pfn; > - > static pgd_t *srmmu_swapper_pg_dir; > > const struct sparc32_cachetlb_ops *sparc32_cachetlb_ops; > @@ -884,7 +882,6 @@ void __init srmmu_paging_init(void) > pud_t *pud; > pmd_t *pmd; > pte_t *pte; > - unsigned long pages_avail; > > init_mm.context = (unsigned long) NO_CONTEXT; > sparc_iomap.start = SUN4M_IOBASE_VADDR; /* 16MB of IOSPACE on all sun4m's. */ > @@ -910,9 +907,6 @@ void __init srmmu_paging_init(void) > prom_halt(); > } > > - pages_avail = 0; > - last_valid_pfn = bootmem_init(&pages_avail); > - > srmmu_nocache_calcsize(); > srmmu_nocache_init(); > srmmu_inherit_prom_mappings(0xfe400000, (LINUX_OPPROM_ENDVM - PAGE_SIZE)); > -- > 2.43.0 >