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 B762D37C0F8 for ; Sat, 29 Aug 2026 06:26:27 +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=1787984793; cv=none; b=DIvuES5X6mvC7xLmOmr1nvrfPvfYlid0UeVA4sljw+ObOpSmvQbwOLl85UL2vEJFfxz6q84dpOxs3s5odEHPU35pTT02OFPgCsMb000UAo0Oxj0DCQbZZCE662/QjL3QpPZGuiu8SPBQdvm/mZXWhdHB1dX8ngd+yHtlPk5FrOg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787984793; c=relaxed/simple; bh=q4GpF3OqPegTQd9cJ2QYPPj8QntQDa9G0gz+GvAYEU8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LFqlYdA91UBgjwSrYR2N235lavhR9T50V9m8nvF1uUuhqgTzPu2Ww6Fl8Dph2DbY5HXWyF3JKtpFtYD0NtnuIOSbbJb9q97roywO4aGYUj4dbGdgCCnut/1fwaaAftZz8LG4GkK2Howx7SuGtnEwbWd8fcdk+UQQBXJhOmQsu0U= 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=jsjnLpbC; dkim=permerror (0-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b=1OzQnMOD; 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="jsjnLpbC"; dkim=permerror (0-bit key) header.d=ravnborg.org header.i=@ravnborg.org header.b="1OzQnMOD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1787984785; x=1788589585; d=ravnborg.org; s=rsa1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=ofQlwmnGw3PEeR1WpbWm08yN0hlGqwWSnQ6hhvtMn/M=; b=jsjnLpbCw9b+YQRpL7k6AorxLExmdr9Hdy7BBBWIsVeGi7qdAwWvz6rFdXNeHlxHhC40gG24OHa8X q4r+GkFBRwkrZe0VNBMBbI5mYXxy/pxFqz6JPChy0XAvqKrWi2hyW89ILRx6XuYocEaivpgAOFL6do /lVwtCZR8IAsxj/OE7QI5ySSim1LeeHOrblwMDr1b9q3DqdhUIwYpUa39jwQLgqnRbJwORvmp3P421 ZtC8ETNXaT2wCMvoBbMLFzQsUbzq+I5/xFEmMx9mih9j1HBrC3WgrF1vAtm/AgD+eABpsLwtSql/vN me9A3YbDbKJpHHXNbrft+bJd3Ih6uMw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; t=1787984785; x=1788589585; d=ravnborg.org; s=ed1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=ofQlwmnGw3PEeR1WpbWm08yN0hlGqwWSnQ6hhvtMn/M=; b=1OzQnMODt3kbVZEmX8qEQpXYBpqpasB80hJcyWyj/sUMqurgo1QetqjwxfcKoGOv4V6KKcG6R9PUA XVuXBLeBw== X-HalOne-ID: 8d795de2-a372-11f1-a4cc-579199b74f77 Received: from ravnborg.org (unknown [2a00:fd01:81e9:6100:cd23:4a74:8afa:914b]) by mailrelay5.pub.mailoutpod3-cph3.one.com (Halon) with ESMTPSA id 8d795de2-a372-11f1-a4cc-579199b74f77; Sat, 29 Aug 2026 06:26:24 +0000 (UTC) Date: Sat, 29 Aug 2026 08:26:23 +0200 From: Sam Ravnborg To: Magnus Lindholm Cc: sparclinux@vger.kernel.org, davem@davemloft.net, andreas@gaisler.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/5] sparc32: move early memory setup to setup_arch Message-ID: <20260829062623.GA44338@ravnborg.org> References: <20260827182757.6856-1-linmag7@gmail.com> <20260827182757.6856-5-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: <20260827182757.6856-5-linmag7@gmail.com> Hi Magnus On Thu, Aug 27, 2026 at 08:24:16PM +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(). > > 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. > Rebasing the relocate kernel patch on top of this would prevent the same code to be patched twice. But the end result would ofc be the same. A few comments in the following. Sam > Suggested-by: Sam Ravnborg > Signed-off-by: Magnus Lindholm > --- > arch/sparc/include/asm/pgtable_32.h | 3 +- > arch/sparc/kernel/setup_32.c | 118 +++++++++++++---------- > arch/sparc/mm/init_32.c | 140 +--------------------------- > arch/sparc/mm/srmmu.c | 4 - > 4 files changed, 73 insertions(+), 192 deletions(-) > > 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/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c > index 795714959da6..e5f1c3ee36df 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 +255,77 @@ 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); > + > +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 last_pfn = 0; > + phys_addr_t start, end; > + u64 i; > > - 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; > + for_each_mem_range(i, &start, &end) { > + unsigned long start_pfn = PFN_DOWN(start); Here for_each_mem_pfn_range() could be used. > > - if (end <= base) > - continue; /* wholly below - drop it */ > - if (start < base) > - start = base; /* straddles - trim the front */ > + if (start_pfn >= limit) { > + if (last_pfn < limit) > + limit = last_pfn; > + break; > + } > > - sp_banks[j].base_addr = start; > - sp_banks[j].num_bytes = end - start; > - j++; > + last_pfn = PFN_DOWN(end); > } > - sp_banks[j].base_addr = 0; > - sp_banks[j].num_bytes = 0; > + > + return limit; > +} > + > +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); > + } > + > + 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_pfn = PFN_DOWN(memblock_end_of_DRAM()); > + last_valid_pfn = max_pfn; last_valid_pfn can be replaced with max_low_pfn in all places. > + max_low_pfn = max_pfn; Likewise, replace all uses of max_pfn with max_low_pfn. Code becomes easier to understand when the memblock defined variables are used. > + highend_pfn = max_pfn; > + > + if (max_low_pfn > pfn_base + (SRMMU_MAXMEM >> PAGE_SHIFT)) > + max_low_pfn = calc_max_low_pfn(); > + > + 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 +356,6 @@ 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 +390,7 @@ 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 75050dfbc2ea..62c41d896421 100644 > --- a/arch/sparc/mm/init_32.c > +++ b/arch/sparc/mm/init_32.c > @@ -39,66 +39,15 @@ > > static unsigned long *sparc_valid_addr_bitmap; > > -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; > @@ -128,83 +77,6 @@ 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)); > - } > - > - 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. > @@ -220,14 +92,10 @@ void __init paging_init(void) > > static void __init taint_real_pages(void) > { > - int i; > - > - for (i = 0; sp_banks[i].num_bytes; i++) { > - unsigned long start, end; > - > - start = sp_banks[i].base_addr; > - end = start + sp_banks[i].num_bytes; > + phys_addr_t start, end; > + u64 i; > > + for_each_mem_range(i, &start, &end) { > while (start < end) { > set_bit(start >> 20, sparc_valid_addr_bitmap); > start += PAGE_SIZE; There are no users of sparc_valid_addr_bitmap, it would be better to drop the whole function in a preparation patch. > diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c > index 3029527a5a9f..272e430f8bd8 100644 > --- a/arch/sparc/mm/srmmu.c > +++ b/arch/sparc/mm/srmmu.c > @@ -884,7 +884,6 @@ 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 +909,6 @@ 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